I have dCS Vivaldi dac and upsampler with clock. I am using Synology 918 and have ROON core on it. I connected Synology to the Vivaldi DAC by USB and also the upsampler is connected by ethernet. I can play using RAAT protocol thru upsampler and also by ALSA USB connection from Synology to the DAC. I do not use any DSP, it is disabled. Buffer in ROON audio device settings is set to default 100ms.
In all those setups sometimes ROON denies to play a new track. When USB ALSA is chosen in ROON, as the new track with new resolution or frequency begins the <1s white noise is heard and the dCS loses USB visibility. It is especially annoying, since to recover the playback I have to switch the DAC off/on or I have to toggle the USB class from 2 to 1 and back to 2, since the dCS does not see the USB port. This does not always happen, only sometimes. When networking input and RAAT is used, the noise is not heard, but the track sound is not heard either. To recover the playback, I have to play a new track with different frequency or resolution and go back to the same track that failed to play and it plays ok.
I experimented what ROON settings should be to avoid the problems. I adjusted RESYNC DELAY to 2 seconds and it seemed to help indeed but it looks only for the tracks with frequency change. The problem however remained for tracks 44.1/24-bit and 44.1/16-bit. When selecting manually playback between those 2 tracks I experienced very often the issues described above.
My idea is if you could use in the core software RESYNC DELAY settings also for situation when the frequency does not change but when resolution changes. Maybe this would help ?
This sounds like an issue with the Linux USB driver on the Synology. Synology is using the 3.10 kernel which is quite old (first released in 2013). Synology has obviously customized it heavily for their hardware so there is little chance that they will be doing a major version revision any time soon. We’ve performed a few updates to the USB receiver code in the Vivaldi DAC and Upsampler since then so I’m not surprised there’s an issue. Unfortunately, I don’t have a solution for you for this particular configuration.
Having said that, I’d recommend against connecting the DAC directly to the Roon core (regardless of platform). Given the processing done by Roon and the poor isolation in a typical NAS you’re potentially funneling quite a bit of noise into your DAC.
If you need the USB connection to the DAC as well as the network connection to the Upsampler then I’d recommend using a separate endpoint device connected to the DAC. Something like one of the Raspberry Pi endpoints would work great.
Although I haven’t seen this specific scenario I have seen a number of similar ones. The upcoming MQA release will include a number of fixes in the network firmware which should help here. With the Vivaldi the resync delay is still recommended if you do a lot of playback where bitrates and sample rates change frequently (i.e. track playlists vs complete albums). On the current released firmware I recommend between 3 and 5 seconds. With the new firmware I’m seeing very excellent results with those values cut in half.
Also, be certain that the RS232 cable between the DAC and Upsampler is connected correctly as there’s some signalling that goes on to improve the speed of sample rate transitions.
the playback by USB seems to be slightly better than thru upsampler at least to my ears in my system, simply I prefer this kind of sound. To fix the problem with USB driver, do you recommend any other solution that could provide similar level of performance to the Synology ? Do you think Nucleus or NUC/ROCK would solve the playback problem with USB ? Do you have any explanation why I experience the problems only when tracks are switched between 44.1/16 and 44.1/24 ? Do you think the problem would be solved if the RESYNC DELAY in ROON setup would be working also for resolution change, not only for frequency ?