Not sure why I didn’t think of this test myself earlier, suggested by Jussi today.
I enabled Roon DSD512 up-sampling and set HQP to ‘Direct SDM’ - I changed HQP settings to xtr filter (NON 2s) and deliberately set it to DSD256, just to convince myself that HQP was essentially in pass-through mode to the ultraRendu NAA.
With Roon up-sampling to DSD512 (via ROCK NUC i7) , the Pro-Ject S2 DAC indeed showed DSD512 on the display and the sonicT i7 (running only HQP Embedded and nothing else) showed CPU usage 0% (as it should, with HQP essentially in DSD512 pass-through mode).
No pops with the above config!
So it’s not a network issue, not a NAA issue, not a sample rate issue. The only variable is Roon DSD512 up-sampling (no pops) vs HQP DSD 512 (pops), both going through HQP and NAA.
Thoughts? Are we now back to a sonicT i7 CPU loading issue?
