Ok. I feel the urge to respond to this all, but I'm not sure I can have a real contribution. Just hunches, and those appear all so often to be right afterwards ...
About shutting down services and all ... no doubts. They help. About the hardware stuff ... hmm ...
It is my hunch that they help creating
some consistent situation for an in fact further fixed environment. Think of a certain type of memory producing better results (SQ) when the other stuff is left alone, but when you e.g. change the PSU you'd have to again find the best memory. Note that I never tried, but I do know what XXHighEnd is doing ...
It is my hunch that whatever you do with the hardware, can be incurred for by software too, which in this case would be the Q1 slider. So what I say is, that when you found the best memory in your environment, this "other" memory can have the same results but with another Q1 setting.
Without reading all what is written on AA about these kind of things, I wonder what the explanation of guys with some insight in this would be. Maybe it all has been worked out, but I doubt it, because I think you cannot have the explanation. And mind you, a better PSU, less consuming memory, better physical stability ... I don't dig that. I mean, not without the good explanation to it. Not when your DAC is at the other end of a USB cable.
In the end there sure *is* an explanation, accepting that it matters indeed (SQ changes). So, personally I don't need proof of that.
My point is, that real explanation would be the same explanation I have, then caused by software.
That's it. My contribution. Not worth much, right ?
Peter