Roon API volume change of grouped zone

Is there a way to access the master volume of a grouped zone (circled in red below) via the API? I believe currently control is possible via separate outputs only. I have implemented this method of separate volume adjustments in a hardware volume control I am developing, however due to the latency of each adjustment, the volume adjustment happens sequentially with about a 500ms delay between the 3 I have in my zone. Not a major issue but it would be cool if the API allowed instant volume adjustment in the same way as the roon remote app works.

Note I am running this on an RPI via the python extension ( and when a hardware volume adjustment is detected separate change_volume commands are run for each output:


Perhaps there is a better way of doing it.

I also tested this for rooDial rooDial a Wireless Volume Knob for Roon with Microsoft Surface Dial - Audio Products - Roon Labs Community

I found no way except changing each output of the zone separately.