In exclusive mode, we send the volume command directly to the hardware driver.
In response to this driver-level volume command, your DAC may choose to ignore it, implement the volume in DSP, or implement the volume in the analog domain. We have devices in our testing environment that do all three things.
I even have one device here where the volume command coming from Roon impacts the volume on a “headphone” jack (analog domain) but not on a “line out/optical” jack on the same device, which remain bit-perfect.
If you have a device that becomes non-bit-perfect in response to volume commands, or that completely ignores them, it’s probably best to use the “Fixed Volume” setting. Same if you have some other hardware volume control further down stream that you’d prefer to use.
But, if you have a device that does clever things with volume commands like the one I described above, the volume control in Roon is useful and makes no quality compromises.
As far as mute goes–being bit-perfect doesn’t matter when playing silence, so we made mute work across the board.
(I’m aware that the fixed volume setting isn’t working properly in some configurations in build 8…we’re on it)