Well, I have done alot of listening in many modes for both of these receivers. I listened to the Denon 4306 and HK 645 on my JBL setup and compared them very closely. Now, both weight around 41lbs. True, Denon has more features. But for sound QUALITY HK beats Denon especially for music. Home theater surround is close, but still the edge goes to HK. Build quality goes to Denon, but SOUND goes to HK for sure. I really could not believe it myself. Denon 4306 goes for around $2000 and I just bought a HK 645 on clearence for $599. Also, when I cranked up the volume at very high levels the Denon's safety turnned the unit off several times. The HK 645 NEVER turnned off at that same level. I also noticed a warm, very smooth sound from the HK. Denon's sound was also good, but the high's were harsh an not SMOOTH like HK. No question the bass control was better with HK. Both receiver's fans were running continously throughout the high level testing. HK 's manual is terrible, but it makes up for it in SOUND. I can only imagine what the HK 745 would sound like!!
Here is my setup:
JBL e100 (FRONT)
JBL ec35 (CENTER)
JBL E50 (SURROUND)
JBL e250p (12" Sub)
All hooked on audioquest 14 gauge speaker wire.
Ironically, I used a top of the line Denon (dcm390) cd player to compare music and a Sony DVD player for Digital testing.