Does anyone have or used the Parasound P7 preamp ? It's both a stereo & multichannel surround preamp that's totally analog. I have 2 of them but have 1 major complaint: Bass & treble controls only work in the front right & left channels. Not the rears or center. In other words you can adjust the "tone" in the front channels but the others stay "flat". Don't understand why it was designed this way & when I contacted Parasounds' service dept, they were very arrogant & condescending in their response !!