Gene, to confirm your question, the 9.1 works with an external amp... hooked to the presence out jacks. It even works with DPIIx. I don't know what it sounds like, as I have had the 9.1 (actualy 9.2 for me as I have 2 subwoofers) hooked up since day one. I should really turn off the second amp to see if there is a difference.