Basically, the sound seemed muffled, almost like I was wearing earplugs. I adjusted the placement of the front speakers (moved them forward so there would be no deflections off the side of my entertainment center), and that made a considerable difference.
I do have a subwoofer (old cheap Sony sub). I'll probably replace it at some point, but bass response hasn't really been an issue.
Unfortunately, my receiver predates the inclusion of Audyssey, so I'm making manual adjustments.
Since adjusting the speaker placement really helped, I guess my only remaining question is do you think a receiver upgrade (with proper calibration software) would make much of a difference? I was looking at something like the Onkyo NR1007, which is pretty affordable now that the 1008 is coming out. Thanks!