My mistake. I assumed you were referring to the CI 720: CI 720 - NAD Electronics. That unit is a combination streamer/DAC/amp. They offer a 3U rack mount that you could mount 6 of them into vertically, though I think each still requires a dedicated power cable.
There’s this thread on issues with it, for example: CI 720v2 - is this actually Roon Ready?. Maybe that’s its predecessor.
The CI-580-V2 looks interesting. Does that show up as 4 distinct Roon zones?
My 8 channel (4 zone) amp is a CI-8-120. It works pretty well.