Allo DigiOne Signature Player review
I received a surprise package in the mail a bit more than a month ago, all the way from Mumbai, India. I immediately knew that it was sent to me by Allo.com as the package looked almost identical to the Katana I received some weeks before. To my surprise there was the latest and greatest DigiOne Signature Player, fully assembled, neatly packed inside. I personally own the original first generation DigiOne that was my first purchase from Allo.com and was very eager to compare them to hear if there can really be more improvement to what I considered already an excellent Coax SPDIF transport. I took my time with this one and put it through its paces; here is my review of the new DigiOne Signature from Allo.com.
The headings are clear and if you are familiar or an expert on some of the topics, please feel free to skip ahead. I tried to cater for readers of all experience levels.
What is this DigiOne thing, and what does it actually do?
The DigiOne products from Allo.com are meant to provide the user with a high-quality digital audio SPDIF output signal, that needs to be connected to an existing external high-quality Digital to Analog Converter (DAC) via an RCA or BNC coaxial digital audio cable. Thus, the output of the DigiOne is not analog audio but still in the digital form and needs to be converted to something you can amplify and actually listen to. Much like what a traditional CD player does when you use the digital audio output signal to your Home Theatre AVR or integrated amplifier. Except now, the digital audio source is not a spinning disk, but a digital audio file served up with a Raspberry Pi single board computer (SBC), converted by the DigiOne hardware to the same SPDIF signal that the CD player would have provided. So, the DigiOne is not a DAC but just a transport, and brings the signal to your DAC.
This enables you to play your massive collection of computer audio files to your HiFi from a low powered, acoustically silent palm size computer. There are many similar devices that can do the same, even your phone, but the focus here is on the audiophile’s needs with little to no compromise on audio quality from the source and upwards, and this gives you the flexibility to choose your own high-end DAC for a more modular system.
In a neat, small and pretty enclosure, you get the Raspberry Pi computer and the DigiOne add-on component boards that is plugged in directly to the Raspberry Pi. The DigiOne receives a data signal from the Raspberry Pi at the bottom and works its magic to deliver an astonishingly good measuring SPDIF digital audio signal that you can feel confident about and feed that to your high-end HiFi equipment that you cherish so much.
To achieve this high-quality signal, timing of the bits needs to be precise and there must be little to no other electrical noise mixed in with the signal that could cause distortion or confusion within the DAC. The latest iteration of the DigiOne product line, the DigiOne Signature, does this in a number of ways. To reduce the noise and get clean power supply, they have separated the power of the Raspberry Pi and the DigiOne Signature by providing two power input jacks to take separate power supplies, one for the “clean” side and one for the “noisy” side. Where the Pi and the DigiOne Signature boards needs to interact, they have implemented the hardware to galvanically isolate the ground and signal conductors between them. There is also a super capacitor that deliver immediate power as needed from its stored energy without needing to “fetch” power from the plugged-in power supply. They have gone further to discard the data clocking from the Raspberry Pi, and then re-clock the data signals received by its own high quality onboard NCK clocks to ensure ultra-low jitter (Allo claims less than 400 femtoseconds) timing of the bits that are sent to your DAC. There are more technical details given in the DigiOne Signature manual. In essence they strived to reconstruct the digital audio signal in the purest and accurate way possible and still provide value to the customer.
Please take note that when the word “Player” is attached to an Allo product, it means that you are getting an all-inclusive kit, containing everything you need to get going. So, I got the DigiOne Signature Player. When you look on the Allo.com website, you can also find the DigiOne Signature (without “Player”) and that is just the add-on component board, and you have to provide your own Raspberry Pi, SD card, power supply and enclosure to make it work as intended. The exception to this is the USBridge product that is also an all-inclusive kit, but where the DigiOne provides SPDIF output, the USBridge provides an audio grade USB port for your external DAC to connect to.
Explaining the integrated Raspberry Pi computer:
I think the main reason for using a Raspberry Pi instead of a full multifunctional general computer is the ability to strip out all the useless software from the operating system and only leave the essential core functionality in place and make it fit for purpose. This is usually based on some variation of the Linux OS. There are so much going on in the background on any Windows, MAC or Linux full desktop operating system that has absolutely nothing to do with processing music. With a bare minimum system, you can allocate all the resources towards your audio processing functions, and also switch off anything else not being used, and enable these low powered computers to excel at audio processing without breaking a sweat and be super responsive and reliable. They use so little power that you can leave them switched on all the time and be ready and waiting for your command.
The best part of all is that these compact purpose-built systems are ready to download and use immediately with very little effort or knowledge needed to get it working. Most of the time it involves loading the system onto a SD card, plug everything in and powering it on, and then wait and follow the instructions on a web interface. These systems are usually developed and well documented by users, for users. The Raspberry Pi online community is very large and very helpful.
The Raspberry Pi has no moving parts, which means it makes no acoustical noise and generates less electrical noise. It has everything you need built in as standard, especially the latest version (V3 B+ at time of writing) that has dual band WiFi AC and Bluetooth 4.2 built in. Nothing else is needed to be plugged in to do all you need. And then it uses very little power and run from a 5V source.
The Pi is MUCH smaller than any full-sized computer and fit in the palm of your hand and can be managed remotely from another device or your smartphone without a screen or keyboard/mouse attached to the Pi, significantly reducing clutter and complexity with your HiFi setup.
Another big reason for using a Raspberry Pi is that it is MUCH cheaper than any full-sized computer. There is not much to lose. When you are done with your current implementation of the Pi for some reason, the Pi can be repurposed for a range of other projects and not become redundant hardware. Its functionality and behaviour are largely determined only by software. One usually only need to load a new system on a SD card and configure a few settings for the Raspberry Pi to do a new job.
The moment you put the Raspberry Pi in the mix, you have endless options to choose from regarding how and where the Raspberry Pi gets the music files from and which software it uses to play the files. It enables you to do all you did before with less/smaller hardware, more efficiently with more flexibility, and even opens up options you have never even considered before. For a small cost you add all these features to a product like the DigiOne Signature and it takes care of everything from obtaining the music data to converting it for you into a high-end signal for your HiFi. Integrating a Raspberry Pi into a product like the DigiOne makes a lot of sense now, doesn’t it?
Software and Operating System choices for the Raspberry Pi.
Choosing software and an operating system for your Raspberry Pi is a very subjective choice. I will only mention the 3 options that I know well and used to test the DigiOne Signature. They are all free software, with ready to use SD Card images.
My personal view is that it does not make any difference which music playing software or system you choose to run on your Raspberry Pi, as long as it is properly developed and configured for audio playback and supports your hardware, the music sounds the same or is not even worth debating. The choice should be mainly based on what functionality you want and how it needs to integrate into your existing systems and hardware.
Then you need to decide if you want to play files from your home network (using WiFi or a LAN cable) that are hosted on a file server or NAS, or stream music from the internet, or have no network connection at all and store the files locally on USB storage or the internal SD card. Of course, you can have all these options available at the same time as well. It is usually dependant on the user’s configuration.
Based on the above prerequisites that you have established, you then choose a suitable Raspberry Pi system to download, copy it to SD card, start it all up and then configure it towards your needs.
I use PiCorePlayer to simulate a Squeezebox Player that plays files from a dedicated networked media server that hosts Logitech Media Server (LMS). This way I keep all the hard indexing and file management work away from the Raspberry Pi making it even more lightweight to run. It only needs to receive the data from the network and play it. This even works well on older generations of the Raspberry Pi and the Raspberry Pi Zero. PiCorePlayer is usually ready in 15 seconds from powering it on.
I have also used Volumio in the past, which works like a Squeezebox, supports DLNA/UPnP, and has a rich web-based user interface. Volumio can also be a standalone player that plays locally stored music files and hosts its own music library, and it can play internet radio stations as well. In the past I was not happy with the performance of Volumio with huge music libraries, but they have come far with their development and the faster Raspberry Pi 3B+ runs it very well. I’ve used it 50% of the time for this review to get a good feel of the latest version and I am very impressed with it. It starts up and will be ready to use in about a minute.
A third option is DietPi and this system is totally flexible and the user has to choose from a huge list of abilities with the initial setup. It will then install everything you selected for you automatically and ask for user input when needed. It supports DLNA/UPnP, Roon endpoint, Squeezebox and LMS, and much more, even your 3D printer with OctoPrint..but that is going off topic now. I used DietPi the least so far.
The above should get you started. But there is a HUGE community on the web with lots of helpful info and opinions. Google is your friend from here on forward.
It’s good to experiment with the different options if you have no experience or exposure, and eventually you will settle on a minimalist configuration that gives you the best experience and reliability for your setup and needs.
Now, let’s move our focus to the actual product.
Unboxing and first impressions:
I am very pleased with the attention to detail paid when these guys packed the preassembled unit. The pieces of foam are meticulously cut out to the perfect size and inserted into the cavities and also layered carefully to cover all pressure points and make the box full and compact inside to prevent box deformation or any squashing of its contents during shipping. Well done!
The box contained the preassembled DigiOne Signature Player, a coax to BNC converter and 2 standard Allo 5V switching mode power supplies (SMPS) that are in my experience very good and much better than a stock Raspberry Pi power supply. It also contains short power converter cables that converts the standard power jack to USB-C male ports.
And here already we see the first difference between the original DigiOne and the new DigiOne Signature. It now takes two power supplies. One is dedicated to the Raspberry Pi computer system and the other is dedicated to the DigiOne that is clearly marked as “clean power”. The idea is to feed the DigiOne its own high-quality power source and keep it separate from the Raspberry Pi (that generates some electrical noise by itself and one of the main reasons we don’t just plug an external DAC into the Raspberry Pi USB ports). This enables you to use a generic cheap switching power supply on the Raspberry Pi. Then you only need one expensive audio grade power supply like a linear power supply or a battery pack on the DigiOne to take it to the next level. At first, I did not have a special power source and used both the SMPSs, but the Allo Battery Pack that uses four 18650 Lithium batteries was sent to me in the last week to try out. The battery pack is their recommended power source. I also received a TeraDak 5V Linear Power Supply (LPS) from China in the last week, which my brother in law brought over for me on his visit. Suddenly the power supply variety I could play with increased 3-fold. Those interested in my long-term impressions with the batteries and LPS will have to contact me in 2+ weeks from now. My current views are based on just one week of listening.
Both power connectors are placed to the side of the DigiOne Signature Player, where the USB ports of the Pi are located. I actually do not like this design choice versus the original DigiOne. The original had all the necessary wires attached to one side of the housing. When you use the internal WiFi of the Pi, or like me use a small USB Nano WiFi dongle, you have all the wires exiting on one side, facing the rear of your desk, hiding the wires and looking super neat. Now you have the COAX cables in the original location but with 2 extra power wires sticking out to the side. Cables just don’t look neat. I prefer not to see them. In this regard I prefer the original DigiOne. At least the cable exits for the DigiOne Signature are limited to only two sides of the housing.
The next thing I notice is that the overall size of the DigiOne Signature has increased from the original DigiOne. There is now a double stack of add-on boards on top of the Pi housed in the enclosure. So, there are now 3 layers of PC boards inside the enclosure. The top main board is jam packed with components. It hosts the COAX connectors, the NDK oscillators, the power filters and regulators, the signal isolators and the USB-C power connectors. I guess there was just not enough space on one board and hence the second board, the child board, was needed for the rest of the components. On the child board it has the I2S to SPDIF convertor, a super capacitor and a power LED that you can disable with a jumper. The Allo DigiOne Signature Player seems to have a size similar to the Allo Katana Player.
The RCA COAX connector seems to be improved. They are now solid copper and soldered to the ground on the board surface that should be a much stronger attachment than the previous orange plastic RCA Coax connector that was held in place with plastic pins and the through hole soldered wire connections.
The acrylic housing of the DigiOne Signature is also made out of thicker panels and the laser cuts are precise and neat. I really like the looks. It is simple and interesting to look at with the insides and LED lights visible from outside. I got the clear acrylic version, but I prefer the smoky black acrylic version as it looks more mysterious, blends in better with black HiFi gear, and hides dust collecting over time on the insides.
Out of experience I stick some rubber feet onto the bottom thumb screws to make it sit firmly on my desk. I think Allo can include some basic rubber or silicone feet you can stick on yourself. Without this, it slides around on the table far to easily and cables pull it out of place just by their weight alone.
The DigiOne arrived with a SD card installed and my unit was preloaded with Volumio. I wanted to see how easy it could be and left it as it was. WiFi needs to be set up over the wired connection first after which you can disconnect the LAN cable. So, I started to plug in the LAN cable and a USB WiFi dongle (more about this later). Then a HDMI cable and a small wireless USB keyboard, just in case there was something to see and configure on the screen. Then I plugged in an RCA coax digital audio cable that was connected on the other side to my DAC. Lastly, I connected the two power cables and powered it all up.
Small LED lights started to shine and flicker with activity. It looked very festive. The screen suddenly displayed the word Volumio in the centre, and later the lights calmed down and it asked for a username and password on the screen. I was a bit confused at this point and did not know what the credentials was that I needed to enter.
I decided to check my router for an IP address for the Pi. There it was, a client called Volumio with a new IP address. I punched this into my main computer’s browser and bam, the beautiful Volumio web interface displayed and was waiting for me. I checked the settings and saw the DigiOne audio board settings were already correct. I navigated to an internet radio station, clicked on it and it started playing! That was super easy!
At this point I knew that the attached screen and keyboard was not needed and was only there to give advanced access to the system if needed. I then configured the WiFi on the web interface and then shut it down. I disconnected the HDMI cable, the keyboard and the LAN cable. Then restarted the device. It now had a new IP address based on the new WiFi connection, and after using the new address in my web browser the same interface was available again, waiting for my command. You can also just try “http://volumio.local” in the web browser as per Volumio instructions but it does not work for me. Don’t know why.
Later during the review, I switched to PiCorePlayer so that I could synchronise the playback with my existing setup on the original DigiOne and to do sound comparisons between the new and the old DigiOne. More about this later.
Setting up PiCorePlayer was just as easy. I took out a new fresh Micro SD card and flashed the Audio Optomized PiCorePlayer image to the card using Win32 Disk Imager. This way I could simply swop SD cards to revert back to Volumio if I wanted to later. I inserted the new SD card into the Pi and started it up. Oops! I needed a LAN cable connection again for initial setup as it has no clue what my WiFi settings are, so I just unplugged power and plugged the LAN cable in. I then decided to redo the SD card image and started from scratch, just to make sure I did not corrupt the SD card when I unplugged the power so unceremoniously while it was busy with the initial setup. It took a minute to redo the SD card image so it was not much effort. Rather make sure than run into strange problems later.
It worked similarly to the Volumio setup. I found the IP address, used it in my web browser and got a web interface where I configured WiFi and selected the DigiOne audio board. Restarted with the LAN cable unplugged and got a new IP address to get to the web interface. Since PiCorePlayer is meant to play upon receiving external instructions from the LMS server, there is not much you need to do in the web interface once you have set everything up to your preferences. It is meant to not be touched further and run headless. At this point you take out your mobile phone and use an app like Squeezer or Orange Squeeze on Android to select music on the LMS server to play to the simulated Squeezebox (via PiCorePlayer) on the DigiOne Signature Player. It just worked without any hiccups like I was used to. It is incredible how easy this has become to use.
I tried DietPi as well. The setup process was similar but was not as easy and would probably give a complete noob a fright. I managed to figure it all out and get it to work similarly. I recommend to first get comfortable with the first 2 options above before trying DietPi. It has much more potential though and might appeal to some advanced users. I myself found some very useful features I liked a lot, but I will not elaborate further. It was not long until I moved back to PiCorePlayer and alternated with Volumio.
A note on WiFi performance.
After some time, I realized that the DigiOne Signature Player came with the latest Raspberry Pi 3B+. This has some notable improvements compared to the 3B without the “plus”. It now has a gigabit LAN port (effectively 330mbps usable) and has dual band WiFi AC. The original DigiOne came with the non-plus 3B version. If you read my previous review on it, you would know I advised against using the onboard WiFi because it gave terrible performance. That is why I used the USB WiFi dongle from the start on the DigiOne Signature Player without even thinking further about it.
But the new “plus” version has a totally new WiFi design. WiFi now operates on its own data bus that is not shared with the USB ports. It also has MUCH better WiFi reception. So, I tried it and did tests vs my WiFi dongle. It gives the same speed and reception strength on the 2.4Ghz band, a massive improvement for the Pi, but it gives me a whopping 3 times more speed on the 5Ghz band! Reception is not so strong but that is the nature of 5G – has less range but more speed. So, I moved to the onboard 5G WiFi permanently and I am super happy with it. Don’t even bother with an inconvenient LAN cable or extra USB dongle with the new 3B+. I found no difference in sound or noise levels between wireless and wired network connection and the 5G wireless with the DigiOne Signature Player and network throughput was never an issue or bottleneck. The DigiOne was located upstairs in the study and my router is downstairs with a concrete floor between the two and a distance of about 10m and at a 30-degree angle… yep, 5G was still going strong.
Equipment used, listening tests and procedures followed:
The DigiOne Signature was left on to play for at least 2 weeks to ensure all electronics are burned in and stable. The original DigiOne I have been using for a very long time and I wanted to make sure there was no doubt that this could be impacting my listening tests.
I have used a range of DACs that I had access to. The DACs I used directly with the Digione Signature and original DigiOne are the Schiit Modi Multibit, Breeze Audio ESS 9018 Pro and the Audio-gd R1.
Because it proved very difficult to do quick switching comparisons between two separate coax sources, when you use the same DAC with only one coax input, I had to rely on a secondary source playing perfectly in sync, feeding my headphone amplifier, so that I can just flick between two inputs with one taking input from the DigiOne DAC and the other input from a stable “reference” DAC. The DACS and devices I used and alternated between to find a close match was the same DACs mentioned above but using different inputs like USB or Optical SPDIF from another Raspberry Pi or my main computer. In addition, I also used the NuPrime uDSD, Allo Katana Player and Allo Boss Player.
I later used a switch box to switch between the two DigiOnes as input to the exact same DAC just to confirm my findings. I was worried about audio quality degradation with this approach but I figured that as long both have the exact same signal path it would be a valid test for comparison reasons. It turned out that this was perfectly fine and I experienced no issues or degradation of sound. And most importantly, I got the exact same conclusions.
I made sure that I used the same cables for the various comparisons and made sure the connections were symmetrical. I also used the exact same power sources when I did direct comparisons and this unfortunately limited me to identical Allo SMPSs to get the baseline testing done. I later introduced the LPS and the battery bank to the DigiOne Signature to see if the results improved, keeping the original still on the SMPS.
Switching between the sources was usually immediate, without any delay to forget how the previous source sounded. Even with this, I found that you needed a lot of hours to listen to the little differences between the DACs and sources. My tests run of many weeks and sometimes I just had to step away for a while as I could not hear the differences clearly anymore as my brain and ears got tired. But after all this, I feel my conclusions are consistent and the tests executed as well as I could.
I would also repeat these tests with different headphones. This is because different headphones excel in different areas of sound. The headphones used was the Sennheiser HD6XX, 2016 Audeze LCD2 Fazor and the Beyerdynamic DT 1770 Pro.
When I found a combination of equipment and a song that clearly showed differences, I made notes and these are some of them.
Jack Johnson – Times like These:
Breeze DAC on DigiOnes, Allo Boss as constant. Voice on Boss has significant more digital grain in Jack’s voice and sounds recessed. Breeze sounds better but similar to Boss on the original DigiOne. DigiOne Signature makes Jack’s voice notably smoother sounding and calmer sounding, but not recessed; and bass control might be a bit better, but I’m unsure.
Melody Gardot – No Man’s Prize, Black as Night:
Breeze DAC on DigiOnes, Katana as constant. Again, the voice! So smooth on the DigiOne Signature. Cleaner imaging overall and more realness to 3D objects like musical instruments and person signing. Damn, the Katana sounds good. Confirmed this with the Schiit Multibit DAC and the Audio-gd R1 DAC.
Tony Joe White – As the Crow Flies:
Breeze DAC on DigiOnes, Katana as constant. Original DigiOne presents a rather messy rock guitar, muddy bass and splashy drums. DigiOne signature cleans this up nicely and sounds almost exactly like the Katana. Not necessarily better or worse.
Luka Bloom – Miracle Cure:
Bass blooms and bleeds into the mids on the older DigiOne.
Eva Cassidy – Wade in the Water:
Eva’s voice is clear and smooth on newer DigiOne Signature. Older version definitely has more graininess and does not sound so natural to me.
Alexis Cole – St Judy’s Comet:
Again as before, voice mostly impacted. It sounds more real and believable, and range of sound is a bit more as if there is more air on top and stage larger on the DigiOne Signature. Slight bass bloom and bleed again on the older DigiOne.
Ladysmith Black Mambazo – Hello My Baby:
Clear grain in starting voice and “digititus” very apparent, with a throaty forced voice on the old DigiOne. Sounds more like a real person with DigiOne Signature.
Sting – Englishman in New York:
Starting saxophone rings out so nice and sweetly on the DigiOne Signature. The Katana and DigiOne signature are clearly next gen units and just adds that last magic beautifully.
Playing with power:
I used my established conclusions formed during listening tests and now added the LPS and battery pack into the mix. I was hoping for a day by night difference between the Allo SMPS and the LPS and batteries. You would certainly believe so with all the overblown impressions on the web and the elaborate designs and prices they want to charge for these audiophile power supplies. I did experience improvements but it was not near day vs night for me. I do however believe this point to some very good news. Allo has clearly put some effort into their design. I can remember clearly the improvement on the original DigiOne and Boss when I used the Allo SMPS vs the stock Raspberry Pi power supply. And even more on the Pi directly when using the onboard USB. The onboard power cleaning circuitry on the Allo products does a very good job indeed. The Allo SMPS sounded more than acceptable vs more expensive power supplies on these devices.
I have to agree that the DigiOne Signature with LPS feeding the Raspberry Pi and the battery bank feeding the “clean” side sounds better. Changing the LPS to a SMPS does not make a definitive difference to me. Swapping the batteries out for the LPS and using a SMPS for the Pi also gives the same result to me. So, it seems that the difference is more notable on the clean side and you can really just use a cheap SMPS for the Raspberry Pi side.
I would say if you can get better power supplies, do so, even if you just want to make sure you have the small things covered at your source. You will notice the improvement in the small details and nuances of the music and the background is slightly darker to make the music sound even more clear and defined, and low volume sounds emerge that you did not know was there or so detailed before. But if you strapped for cash, use the standard Allo SMPS. You can upgrade later, they are cheap enough to get for the interim. The power supplies certainly did not make me enjoy the music less. Sometimes I also feel that doing extreme or minute tweaks steals from the experience of just listening and getting lost in it. I would however recommend to just get the battery pack if you are being distracted by the thoughts or worry that you miss out on details and enjoyment, and then test it for yourself. The battery option is much cheaper than the LPS.
Interesting DAC stuff:
My R1 DAC is a very recent addition. When I redid some of the tests with it, I felt that the older Breeze Audio DAC revealed the difference between the two DigiOnes more clearly. This was strange and concerning to me. They are completely different designs, but I would expect the better R1 DAC to be more resolving or indicative of the differences. It sounded better and more pleasant than the Breeze, but it was all almost at the same level of better. I read something on the Audio-gd site that might give a reason for this, and it is about the FPGA chip they use in the R1:
The FPGA in the R-1 is responsible for:
1. High performance SPDIF interface, replacing traditional less good performing SPDIF interface chips like DIR9001, WM8805 or AK411X, etc.
2. Full re-clocking process with FIFO design applicable on all inputs. This way the output data keeps fully synchronized with the clock signal to reject any jitter.
So, it seems to me like its doing something to the SPDIF signal similar than what the DigiOne does. That would certainly explain it.
Why am I pointing this out? So that you understand that not all DACs are created equal. The DigiOne Signature will not work miracles if your DAC has a bad SPDIF implementation. Same with USB. I think the biggest improvements will be on less complicated DACs. For me, its about making sure that the signal I start with is the best I can afford while being still practical and getting value for money. This way I can use any DAC with confidence. I know I am not spitting out garbage to my DAC and if I find issues with my sound it is likely somewhere else.
It is very clear to me that the DigiOne Signature is an improvement to the previous version.
It is not worlds apart. If you have the older DigiOne, maybe think about getting the USBridge to improve your USB source as well and have a variety. If you are set on SPDIF inputs and don’t like USB and its complications with drivers and power noise, and don’t care for DSD, then the DigiOne Signature is still worth the upgrade. If you get the all-inclusive kit, the upgraded Raspberry Pi is also a big improvement in terms of WiFi and processing performance. And the construction quality is definitely better with improved connectors and a sturdier thicker enclose that’s beautifully made.
If you do not have a SPDIF transport and need one, I can’t think of something I would recommend more. This provides you a lot of value and quality at the price. You can go check out YouTube for Hans Barkhuizen’s review and judge for yourself.
To me the sound improvements are mostly in areas where the sound is sustained for a while, like with vocals and brass instruments where they do a fade on a relative constant note. Where digital graininess, edginess and sharpness would be very apparent the improvements are most notable. Few times I felt that the sound presentation or details were improved, but not much. Like with the comments on the blooming and bleeding bass notes. It just cleans things up nicely and makes it sound more natural to me.
I guess also it makes sense as this device is operating in the digital domain. So, any improvement that manifests would be to do with timing of the digital signals and to accurately represent the zeros and ones. The less errors the DAC makes at the receiving end of this signal, the better the music is reconstructed. If your plots on the analog signal graph is not accurate, it will surely change the smoothness first and then more severe sound altering effects will follow. But this is just how I picture it for myself and its not scientific at all.
If I had to give the Allo DigiOne Signature personality traits, I would think of it as gentle, confident, mature, accurate/calculated, cool and quiet . Its not offensive or abrasive, its just nice to be with and have around.
Well done Allo, I am impressed with this one. The DigiOne, Signature.