I've been upgrading the speakers around one of our TV setups and am looking for any advice/suggestions.

I've got a HTM200SE in the middle and two CBM170SE in the front. They're about 8 feet apart and all about 5 feet from the viewing area which is a couch. I've got a couple of old Optimus LX-5's for surrounds behind the couch.
Immediately behind the couch I've got a Hsu STF-1 and about two feet behind that is a wall.

I was using a SPL meter to try to even out the volume and have about +5db on the center and +4db on the surrounds using the test tone on the receiver set to the volume that we usually listen to (about 70dB). Does that sound about right? Any suggestions for improving the sound in front? My receiver is pretty old so it doesn't have a lot of adjustments - the crossover is fixed at 90Hz and I've got the crossover on the subwoofer set at 80Hz.

By the way I really like the sound out of the HTM200SE. Dialogue sounds much clearer and understandable compared to what I've been used to. Kudos to Ascend on such a great and inexpensive little box.

I don't really have a good idea about how to set the volume on the subwoofer. The instruction say to adjust it until it "blends in"... but I'm not sure I know what that's supposed to sound like I've just been tweaking the volume control while watching the movies since it's right next to the couch. Any suggestions to figuring out the right volume setting?