Roon is bit-perfect. HQP is not bit-perfect. Let’s quickly defined the accepted, or I should say majority, accepted definition of bit-perfect.
Perfectly understood. Player may play bitperfect, if not the sampler is set to do anything, but what I ment, is that the HQPlayer player part of software does a better job compared to Roon playback.
Bit-perfect is taking the source PCM or DSD bit-stream and handing it to the DAC unaltered. This requires no DSP, no volume (amplitude adjustment, no up / down-sampling. The whole point of HQP is to not hand the “bit-perfect” bit-stream to the DAC but alter it in ways that influence the way the DAC works… generally to assist in providing a more pleasing output of the DAC to the listener.
Also perfectly understood, no objection
This is not true. Every DAC has filters and internally up-samples. Few DACs are NOS or allow for NOS mode. Why do DACs change the bit-stream ahead of the actual D/A operation? To improve the output.
That part does not belong to the receiver, does it? It would be the DSP section, very inferior compared to the HQPe DSP?
The bit-stream itself is not changed. That is, the 1’s and 0’s in a specific order is not changed. Depending on the streamer, the output might differ slightly influening what you hear at the DAC but if you’re running this through HQP then the bit-stream is altered by HQP so you’re no longer “hearing” what Roon is sending; you’re simply hearing the output of HQP (which is no longer bit-perfect to the source).
OK, so after reading the comment above, I simply turned of everything in HQPe in terms of sampling, filtering and bit depth conversion. Just the onboard RME DSP, to get the volume and other functions needed. HQPe player section out vs. Roon player out, same DAC same setting. HQPe player section with the entire DSP bypassed sound better (at my home). Further, if we take the example WITH HQPe DSP active, since the DSP section in HQPe is set exactly the same irrespective if I playback using HQPe player section or Roon player section, that would tell the difference too, but in order not to be misunderstood any more, I simply bypassed everything except HQPe playback vs Roon playback. No DSP in either program, just DAC (sounded crap btw, when one get used to the magnificent HQPe DSP. Hard to listen to anything else nowadays)
No one is immune to this.
And your expertese in that area is?
This is your bias. You can have a bias for and / or against. The fact you mention price and “high-end” at all means you’re aware of things in your evaluation.
Off course I am aware of it, but that does not raise or lower my expectation, being autistic is not being cut off from the world around you, rather the opposite, difficulties to filter (meaning the mind input filter that normally boasts or choke the input storm around you, hence cutting out sections in reality in your perception, when the autistic person filtering is not as effective and subsequently do not filter as extensive as the more normally functional being.) and perhaps also lack of social skills, where my bedside manners could improve significantly. You can however rest asure you’ll never suffer from that short coming … 
You didn’t describe exactly what your sources and playback chain is when making this statement. Maybe if you described exactly the chain in your listening tests the community can assist in helping you understand why you hear a difference.
I will see if I can do this, It is more than a few days work as I will have to disassemble almost every device and photograph each and every improvement in power management both inside and outside, re-designed grounding of the devices, replaced and increased power buffers to much higher specs locally in most circuitry along the way with zobel net and increased decoupling, etc, etc Perhaps you can give some good suggestions in that area, too. The electro-engineer in me works double over time to trace as many reasons to inferior signal integrity as possible, to get music signal clean from any debris deriving from the electronic circuitry. The only part I have accepted the manipulation of signal is HQPe DSP section, because Jussi is able to make music sound like music. Not everything. There are too much modern productions completely wasted due to sloppy technicians and producers trusting the compressor and limiter more that doing the old school mix work right prior to mastering. That means that the level of “stuff” sounding in my rig, part from the music, is very, very low! A worn kliché; pitch black?
Hard to build those toys together, you know … 
and chocolate really tastes … bad 