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Playing Roon over RAAT - Does the server matter for SQ?

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In every Roon setup, the audio file playback is performed by Roon core. Endpoints only receive the final audio stream that Roon bridge receives and turns into PCM / DSD / whatever... Every Roon certified device has Roon bridge in it (plus some additional integration I believe). Even when you run Roon from a single machine and just send the audio to DAC e.g. via USB, the way it works is the same - Roon core does the playback, this is then transferred via RAAT to a Roon Bridge component that turns it into digital audio signal.


In every streaming setup I tried, the quality always degraded when Roon was in the mix. Either it does something weird during playback, or there is something in the RAAT protocol, but that is my experience. Even when using it with HQPlayer, it's still worse than using HQPlayer alone - again because Roon pushes it's own continuous audio data stream to HQP, it's not just a remote HQP controller.

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I don't know the answers, I'm not a Roon developer. I'm just describing my experience based on comparisons made on my setup. And I've been testing lots of setups in the last year or so, listening and comparing each of them quite extensively. Everytime Roon was in the mix, the quality got worse. I don't know how to explain it. And I don't think I have some expectation bias here because I actually wanted Roon to work in my setup due to its superb interface. The only thing that improved Roon sound for me was when I was running it on Euphony OS. Apparently bit-perfect is not the only thing to look for. I believe it also matters how the data is processed before it's sent out to an endpoint.


One example that makes me think that there is something wrong with Roon sound quality: I've ended up with a dual PC setup. Both PC's are running on Euphony OS to make things even. Both PC's are Intel NUC's, powered with exact same LPS. 1st PC works as a server - either in Roon mode or as Euphony's Stylus player. 2nd PC runs in HQP mode and connects to USB DAC or an endpoint via NAA. When running Roon -> HQP, the sound quality is noticably worse than when running Euphony Stylus -> HQP. The only difference between the two scenarios is that in the Roon/HQP setup, Roon sends it's own continuous data stream to HQP. In Stylus/HQP setup, Stylus only acts as a remote control and it's HQP PC that downloads and buffers the stream before playback (either from local files or stream services). Logically, that makes me think (and hear) that there's just something wrong with Roon streams.

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Forget about NAA. I was testing it also while having the HQP PC connected to USB DAC as mentioned. And it does not matter anyway. Again the only difference between the two scenarios mentioned was in Roon continuously streaming to HQP vs. HQP grabbing the data files on its own, not relying on any external continous data stream. Whether HQP was connected to USB DAC or via NAA to an endpoint does not matter in this comparison as that was not changing when switching between the two setups.

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I don't know if I'm explaining this wrong or what it the problem here. So I'll try again - when comparing the two setups I mentioned, it does not matter what goes out of HQP. The only thing that was changing was what was going in to the HQP. Roon stream vs. HQP getting the data on its own.


I have no idea about your expertise in digital audio playback, but this is my experience. And in my experience it's not just about having a bit-perfect data stream. It also matters how that data stream is created and how the data is processed before it's sent out. Not sure if you ever tried to run Roon Core on an OS like Euphony. Again, I'm not an expert on OS and audio kernels, but Euphony is using a modified Linux kernel specifically designed for audio playback, e.g. like Audiolinux. The focus is on timing, latency, interrupt requests, etc... that's all I know. And I can hear a clear difference, same as everyone else I talked to who tried Euphony. In the past I was also running Roon on NUC/ROCK only and thought it can't get any better, because it's all bit-perfect. Well, I was wrong.

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17 minutes ago, miguelito said:

Via USB that is not necessarily shocking: Roon is taxing your CPU more than HQP alone.

What do you mean exactly? I am upsampling to DSD using HQP, so the load on CPU on HQP PC is significantly higher than on the PC that's running Roon or Euphony Stylus. The USB DAC was connected to the HQP PC as output obviously, so once again - changing between Roon or Euphony Stylus as an input or control method for the HQP does not change anything in the HQP output. That is defined by the HQP settings that remained the same when switching between the two mode.

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2 hours ago, AudioDoctor said:

My only explanation for this was that with the desktop OS on a Mac, there was too much other processing going on in addition to music playback versus the Linux server OS which has next to nothing running other than the barest of essentials to run and play music.


In my experience there was no difference in sound quality while running Roon on standard Windows (where you have lots of other stuff) vs. e.g. Roon's ROCK (which is a minimal Linux OS already).

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  • 4 weeks later...
  • 2 weeks later...

Just to add on Roon Nucleus - I don't think it is any different than if you build NUC with Roon OS / ROCK yourself. I think I remember reading on Roon forums where the Roon guys were saying it's basically NUC in a passive box, just pre-built, for those who just want to buy a Roon Core that is ready to plug and play. I believe the only difference vs. ROCK is they optimized thermal management, so it's slightly different version of the OS, but the Roon guys said there should not be any audible difference.

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