Meridian Speaker control volume and output

I have one Meridian DSP5200HC and nothing else meridian - I have an Allo DigiOne Signature (inc RPi4 4GB) and a Nucleus+ as Roon core.

I have connected
Allo DigiOne SPDIF out to Speaker SPDIF Digital Input 1 And
Allo DigiOne running DietPi USB port to Usb-Serial (pl2303) to Null Modem cable to RS232 on Speaker

Does anyone know if I can play music out through this speaker and control the volume of course?

I suspect you will have to implement VC in Roon but for better help, you should go to the Meridian forums. Very helpful and very knowledgeable in their realm:

Thanks - i will try