This looks like a very old thread. If it is any help to others - I am still quite pleased with my really old AVM20 - terrific functionality better than anything else, IMHO.
Only drawback is that I found it benefitted slightly from power conditioning (the only component I have that does) - however I have an Apple Mac Mini plugged into the same set of wall outlets as the system - so the switched mode power supply for this PC could very well be the culprit. I also migrated to this mere DSP HT multi-channel preamp as a source from other much higher end (but limited functionality) dedicated sources such as high end CD player and high end analog preamp. I use the DAC in the AVM20 to feed everything else. I did not look back.
My philosophy is similar to
this (see Steps to Great Sound) and my observations are similar
this (See Blind Listening tests).
Perhaps I am lucky to have tin ears!