I ask again....are you using Logic 7 on your HK? You see, I used to own a Fosgate Audionics 3A THX/Harman Kardon AVP1 prepro...it has some of the best surround sound of anything I'd heard. Then I upgraded to the Citation 7.0 (Six Axis), HK expanded on this with Logic 7. These modes are very immersive compared to the modes on other equipment. I'm wondering are you missing that in the Integra?
I recently switched from using an Onkyo receiver as a prepro to a Yamaha Aventage - and my B&K amp couldn't be happier!!!! Much better match, even in stereo listening.