Volume control Roon. vs audio amp

David_Lawson1 · September 30, 2021, 11:10pm

Continuing the discussion from Volume control options affecting sound quality and volume levels:

I have a ac Mini M1 and a PS Audio Stellar Strata. I used to set the Strata volume at 50 then control the volume with Roon. I thought I would try setting the volume to fixed and control it with the Strata, I couldn’t believe the difference in audio quality, everything just opened up, more bass better soundstage. It is less convenient not being able to use my tablet or iPhone, as in listening from another room but I’ll get used to it, the change in SQ is amazing. Anybody know the reason why??

Volume control options affecting sound quality and volume levels

My DAC (Musical Fidelity M6siDac) is in locked position (function that gives volume control to amplifier) and I can only change the volume either manually from my integrated amplifier (Musical Fidelity NuVista 800) or digitally from Roon. I prefer to always have the chance to use my iPhone Roon application to control the volume and not just rely only on the amplifier’s control so I have set Volume Control to: “Device” and not “Fixed”. I have read though that I compromise quality this way and that the best is “DSP Volume”. When I tried “DSP Volume” the first thing I noticed was that the Signsl Path changed instantly to: “High Quality” from: “Enhanced” with everything else unchanged. But with my amplifier set even to the maximum volume and the maximum DSP Volume from the Roon control iPhone app) there was a VERY low maximum volume, nothing close to the real maximum that I can achieve otherwise. Am I doing something wrong with DSP, is there a better quality when using DSP Volume?

AceRimmer · September 30, 2021, 11:17pm

Can’t say as I know the reason why but I experienced the same effect.
Had Roon volume set to fixed for months now after hearing a similar leap in sq by using the analog volume control in my dac.

Sure someone will be along shortly to tell us bits are bits and we are just imagining it all…

David_Snyder · October 1, 2021, 12:14am

Haha. Hopefully not. Unfortunately, all “device volume” implementations are not equal. Some are implemented with firmware that does not do proper dithering, etc., providing less than optimal results. If you want to control the volume inside of Roon, ignore the Green dot in the signal path and try DSP Volume, if your endpoint supports it. The math used is high-precision and does use proper dithering.

Some things to be aware of. That code required to implement DSP Volume is not run on Core; it’s run on the endpoint device. This means that instead of your beefy Intel Core i7, a lowly Raspberry Pi (or similar) is doing the work. My understanding is that DSP Volume had to be implemented on the endpoint to minimize latency for volume settings. Otherwise, there would be a significant delay in volume changes, possibly resulting in hearing or speaker damage.

Because DSP Volume is implemented on the Output device, there are limitations. Unlike Headroom Management and Volume Leveling, which happen on Core, DSP Volume does not support native DSD or MQA. If you have DSP Volume enabled, Core will convert DSD to PCM automatically. MQA signalling will not be passed down to the DAC. Sonically, these are minor issues, IMHO, but everyone has different priorities.

I encourage you to read this white paper, which discusses the math and Roon’s implementation of DSP Volume in more detail. After reading it, I became quite a bit less bothered by the dreadful “Green” light in Roon’s signalpath.