My setup -- I'm confused

I think you misunderstood why I was asking the question. I am not suggesting anything nor do you need to justify your reasoning of wanting to solve this issue with me. I am sorry if it came across that way, I certainly did not mean it to. I was asking because if the volume control slider works, then we know it is possible to control the volume using the ⌘ + UP Arrow and ⌘ + Down Arrow shortcuts and could just focus on that and why those shortcuts don’t work. I use a Roon ready device and an iMac so I was going to try and help

Sorry AoD. I’m happy to have your help. Didn’t intend to come across as argumentative.

When I’m in Roon, and use Command up/down keys, I get a small pop-up window that shows the “db’s” going up and down, but there’s no accompanying change in the actual volume of the sound coming from the speaker.