Volume control on Matrix X-Sabre 3

I cloned RoonCommandLine a few hours ago and have had good success with several devices and integrating Siri control via Shortcuts. On my Matrix X-Sabre 3 streamer, absolute volume settings that are positive or negative values sets the volume to 0 (full volume since the device volume control is 0 to -127). I do the obvious workaround:

% roon -v r:-127 -z "Matrix"

% roon -v r:87 -z "Matrix"

To normalize to -40. My Kef LS50 Wireless II respect the absolute volume adjustments.