I have been playing with the DigiOne with almost a month now, and I’ve been able to listen to it with a variety of DACs I do know well.
I’ve never been a huge fan of S/PDIF interface, and I always preferred to use good old USB or I2S when it comes to PI. This is because I believe that shorter the signal path, the better (as you might know from my earlier posts).
Nevertheless, I decided to free my mind from the above prejudice and use an analytical approach with the DigiOne. So, my first step was trying to understand why Allo released an S/PDIF transport that costs about 3 times than similar gear: I know them too better to think they are overpricing, or adding useless components to their boards, so I was curious to see the rationale behind their choice.
Just from a visual inspection you will immediately notice that this board is literally filled with components. I was just wondering why all this stuff for S/PDIF…
From what I’ve understood Allo’s design is based on 3 principles:
- Completely discard the shitty Raspberry Pi clock, and instead use the DigiOne as a “Master DAC”. By doing so the clock (crucial for the time-domain musical message) will be way better than what the Raspberry PI can offer. This is achieved by placing 2 high quality clocks.
- Clean the Power supply coming from the raspberry PI through hi performances DC regulators and filtering capacitors. As always, the cleaner the power is, better the musical outcomes (Signal to noise ratio).
- Isolate each stage of the signal path: there is a galvanic isolator separating the Raspberry PI from the clocks, and the clocks themselves are isolated from the WM8805 (which is the S/PDIF transmitter).
Allo themselves quote that the DigiOne, in fact, is “a master codec with digital/electrical/ground isolation from RPI AND wm8805 and a reclocker”.
I definitely see the advantage of setting the DigiOne as a master clock and cleaning Power Supply as much as possible (which has been a tradition by Allo since the Kali, and IMHO this should be a precondition of every good audio product). I, however, do understand less the advantage of galvanic isolation with S/PDIF, but this is just my lack of knowledge.
So, on paper we have for sure the best implementation of an S/PDIF transport shield (no-one has master clocks, PSU cleaning, re-clocking and galvanic isolation altogether). But how will it sound?
I tried it on 3 “good enough” DACs, which I usually use connected via USB, in order to compare the outcome of the total chain.
I was impressed: never thought S/PDIF could sound that good. My previous experiences were with other shields and there is a very evident difference. Especially for the things I do care about: detail, soundstage and musicality.
Basically, for me at least, the DigiOne has become the only S/PDIF source that I would have in my system. I find the same level of enjoyment that I do have with the Mini86 and ipurifier (on the same DAC, but connected with its XMOS based USB receiver). I won’t be making any further comparison because it will be like comparing apple and oranges (the implementation of the USB Receiver and S/PDIF receiver of the same DAC can be of different quality level).
So, sonically speaking, well done Allo: this is the only S/PDIF I managed to actually like.
Now, what I don’t like about this. I would have preferred to have a way to feed the DigiOne and the Pi separately. Allo claims there is no need (and they are probably right, considering the DC regulators and galvanic isolation) but I think this is anyway a Nice to have feature.
Then a side note, we got various reports (and I was not able to re-create that situation in my system, or just did not notice) that on some systems, when changing sample rate, the first bits of a songs were not being played. Allo quantifies the delay from 25 to 250ms. Considering this happens only when you change sample rate, and it might be solved in future software updates (given is not an hardware limitation), this is just a minor issue.
So my conclusion is: the DigiOne is expensive when compared to similar solution, but it’s definitely worth every penny of it. What we have here is something that was not designed to sound good, but to sound as best as possible (on Raspberry PI), and this is not yet another case of over-engineering: they made clear design choices which my listening impressions confirm to be correct.
To me, the DigiOne (or DigiOne Player, if you look for a complete player) are the best choice possible as of now if you own an S/PDIF DAC, or if you know for sure that the implementation of S/PDIF receiver in your DAC is superior than the USB side.
Again, and I start to repeat myself here, bravo Allo!