So I have a question for ya, for clarity sake:
What is the Sony AF-7? Google is not helping me here
The mirage 7-msi, is there a specific model for this one?
Quite the impressive setup, thanks for contributing to the madness!
Also, let me know if I missed anything aside from the 2 I already asked about.
It sounds like your highend may be suffering more than anything else. Have you confirmed that your speakers are capable of outputting those sounds? (I.E. reducing the volume and getting close to the speakers to see if you can spot the details)
My theory is it may have something to do with either nodal alignment, or sound treatment. However, if you have tried my test, then it may be something with the amplification, or the preprocessing of the audio. Those Polks should be capable of full range audio, maybe with the exception of a bit of manufacturer tuning for specific output.
Another suggestion may be try messing with the outputs your speakers are connected to on the receiver. I noticed with my buddy's setup, he had some issues where a preset audio mode was doing some processing to essentially remove certain frequencies from certain channels. Especially since you are running what appears to be a 2.1 channel setup on a 7.2 channel receiver, there may be some preprocessing on the head unit that is just cutting frequencies given a specific audio mode.