Douk Audio U2 (XU316) - does macOS system volume control work over optical out?

[hajir]

@Douk Audio
Hi, I'm considering buying the Douk Audio U2 and have one question before I order. I'll be using it with a Mac, connected via USB, with the audio going out through the Toslink optical output.

My requirement: the Mac's own system volume slider and keyboard volume keys must still work to control the volume, not grayed out/disabled and no software workaround.

I understand this depends on whether your firmware has "master volume control" enabled in the USB Audio Feature Unit descriptor (I think earlier XU208-based U2 units supported this, and I want to confirm the current XU316 model still does).

Can you confirm:
does the volume slider in macOS Sound settings work (not grayed out) when using the U2's optical output, or is the digital output fixed-level/bit-perfect only?

Thanks!

 

[Keith Flanker]

FWIW the XU316 version still exposes the UAC2 volume control - see the earlier thread here about USB to S/PDIF with source volume control, where people confirmed the OS volume works with this unit. So on a Mac the slider and keyboard keys should attenuate over the optical out. If it ever shows up inactive, that's a firmware/descriptor thing, not a macOS limitation.

 

[hajir]

For anyone else looking up the same question:
I just tried both Douk Audio U2 and U2 PRO on an Apple M1 Max running Mac OS Golden Gate 27 and both units take system volume controls as expected.