sr6004 vs VSX-23THX vs avr3310ci vs HK avr3600 vs tx-nr3007

I'd say buy the UPA-7 and take a look at the Onkyo SR707. It has a great set of features and Audyssey to boot and you'll save a few bucks over some of those other AVRs. If you will be using only 5 channels Emotiva has their newer UPA-5 amp available now.

If you included the NR3007 in this search why haven't you also included the Pioneer Elite 25 instead of the 23? The ICE amps are a different animal altogether. It also warrants a look IMO, along with the others you have listed. Also realize that the Onkyo 876 can be had new for a little more than the 707. I just read a test report on the Onkyo 807, the model above the 707 and its amps just did not measure up to previous Onkyo models with ALL channels driven, so I doubt that 707 would. There was a drastic drop in 5 channels driven as compared to 7 channels driven, granted you will not be using all that power at one time, but it also leads one to believe there is something going on in their power supply. Not trying to derail Knuckleheads choice by any means and for the money it problably is a good AVR, its just that for the same money or a little more ther are some "proven" models available. Heck there's a member here that selling a 805 for $475, that's the real bargain. Check out the AVS classified thread. Thereis also a 3310 there NIB that would fit the bill. Good luck and please realize these are just my opinions. Yours may surely differ.