You’re very welcome here and I’m looking forward to the discussion including measurements.
Clearly even the simplest measurements were not taken before they choose to sell the device with iFi power supply as a package.
You don’t know what tests the developers performed. No measurement can tell you that. Please try to avoid this kind of unwarranted conclusion as it lowers the quality of the discussion and reduces the prospects of a response from the developers.
I was surprised at how little switching power noise came through from your laptop. The whole point of using an Ethernet network endpoint is supposed to be to avoid the noisy computer environment, yet your measurements suggested it would be better to have a laptop next to the DAC than a specialised device. The only other laptop measurements I’m aware of were these ones by Archimago. He speculated that the increased noise for the Aspire may have arisen from increased processing.
I use a BRIX as a server for Roon and have avoided putting it next to my DAC because of concerns about power or processing noise. I initially ran a 5m USB to the DAC, later used a CuBox-i (switching supply) and now the mR (iFi) as NAA for Roon/HQP. It would be interesting to compare measurements of all four configurations.
Gianluca has suggested in the other forum that your playback problem with HQP may be because the internal audio device is busy. Are you running another audio program ?