For what it's worth, I tried the D-Verb test outlined here:
http://www.pro-tools-pc.com/performa...ing-pro-tools/
I followed the steps exactly with the only difference being that I instantiated 10 mono D-Verbs in step 12.
The configuration of the iMac Pro I used is in my signature (10 core/64GB/2TB/basic graphics). I have done all of the optimizations found here:
http://avid.force.com/pkb/articles/e...Optimize-10-12
At a 64 sample buffer, I got 141 tracks to record for 10 minutes without breaking up. The CPU meter was at approximately 85%-95%, occasionally spiking up to 100% and lighting up red (but audio not breaking up). That is 1410 mono instances of D-Verb.
During the 10 minutes tests, the iMac Pro was dead quiet. I checked by putting my ear near the top of the monitor. I had to do that because the fan noise in the room from the Sonnet chassis and the HD Omni interface was all I could hear. The Omni is on my desktop about the same distance as my iMac Pro and the Sonnet is under the desk. These two fans were not obnoxiously loud, but that provides a basis for comparison since some people reading this might have one or both of those devices.
Oddly, when I stopped recording, deleted the recorded clips (I ran several passes of the test to converge to 141 tracks, so there were numerous clips created), and permanently cleared them from disk from the clip list, the fans on the iMac Pro kicked in. It was a gentle whirring, less than the Omni or Sonnet and less than any PC case or CPU fan I have experienced. Obviously, tolerances for noise are subjective, but if that is the extent of the fan noise, it is not at all a concern for me, and I record vocals and acoustic guitar within a few feet of my desk.
If anyone has any other suggestions for how to push the iMac Pro to provoke more fan noise, I will gladly try them out.