Regarding Sound Quality of Volumio 2 vs Volumio 3, I find this discussion really interesting, but I don’t have a clear explanation for you guys.
Let me do a bit of background story.
At the time of Volumio 1, I was really on a quest to understand what parameters, settings, kernel tweaks could make a difference in Sound Quality. Since, at the time, I just started Volumio I had the feeling I owed the community as much objectivity as possible, without falling into the (easy) clichè of “special recipes that makes sound better”.
So I started to study all literature I could find online, and surprisingly enough, there was not much to it.
The only things that would make a difference were:
- Making sure sound is bit-perfect (avoid resampling, volume control etc)
- Making sure you’re not messing with I\O and priorities at kernel level
- Making sure you would use a packet size which would not make the PI USB BUS (yeah, PI 1) go nuts and drop packets.
The most promising, however, thing to all that was RamPlay (aka load tracks into RAM and play from there). I was sure that for me it made a sonical difference.
I wanted the proof of that, so I went measuring it (using a 30k Euros Audio Precision equipment, courtesy of Audio Review, one of the most respected audio publications in Italy and Europe).
Result: no matter what combination of kernel settings, Ram Play or whatever I did. There was not a measurable difference (both in periodic and stochastic jitter).
So I was back to square one. I could swear I could hear a difference, but that difference was not measurable. Hence, not demonstrable.
So, from there on, I decided to not follow ghosts and just try to follow sensible principles of bit perfect playback. This in order to better focus what I do on something that could impact positively everyone using Volumio and also because I feel the responsibility of delivering a sensible, genuine approach without selling “magical recipes”, which might be true only for my ears.
That does not mean that those difference in quality do not exist, but since I did not manage to condense them in objectively repeatable parameters, I just don’t focus on them.
Now, coming to what might cause such difference, there are few suspects:
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Volumio 3 uses a newer kernel, where the alsa subsystem had quite a lot of changes. This might have improved playback efficiency (at kernel level), which might have reduced jitter. It would be interesting to know if those that feel a difference are using USB or I2S DACs.
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Volumio 3 uses a new sound engine, which is bit-perfect, but in some cases changes the buffer and packet size of audio, and keeps them constant. This might as well impact positively jitter, but this is just a mere speculation.
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Lot of packages (including core ones such as MPD, alsa, etc) have been upgraded. This again can have an impact on playback.
From what we hear (here on the forum, on emails that we receive as feedbacks) there seems to be a pattern: 8 people out of 10 report that Volumio 3 sounds better than Volumio 2.
In all honesty, this was not intended. Our goal is and has always been bit-percfect playback, which in an ideal world, should result in the same sound.
Obviously, that is not true, and I am interested in finding the reason why.
If someone has ideas, measuring equipment, or knows someone who knows someone, let us know!