Using my i7 server and convolving 1 Zone without upsampling I get a Processing Speed of > 100x (display ceases at 99.9):
Adding upsampling to 352kHz drops that to 12x:
On that basis my guess is you’d be fine with an i7 7700 convolving into 13 zones without upsampling.
I’d suggest using a larger form factor and Windows 10 or Linux if it’s going into a server room. It might not be as simple as ROCK but you’ll get more fan control and monitoring, so you can check CPU load and temperatures directly.