Let me give you some pointers, but these are purely personal.
1. Onkyo. I like the Onkyo sound, maybe because I have been using an Onkyo receiver for a long time. It is powerful and the clarity of dialogues is very clear. Their separation is really good and with the power they pump, you can hear every sound and whisper very clearly. Onkyo may be a bit muted in low frequencies, but that suits my ears. Onkyo, as far as I know, does not filter any sound, and sends it raw to you. You can get a bit of ear fatigue after a while. (It looks as if I am an Onkyo fan
, no?)
2. Denon. Very similar to Onkyo, as they compete very closely with each other. Denon's sound is more refined than Onkyo as I suspect they fool around a bit to make the sound 'pleasant' or muted. You can watch movies for 8 hours and not get any ear fatigue.
3. Marantz. This is a different beast. With a lead in two channel audio, Marantz brings the same refinement in sound to their AVRs. No ear fatigue, and clear separation and clarity at all frequencies. They could be more realistic in terms of their power output.
4. Pioneer. Again in the same league as Onkyo and Denon. When they started they really had to fight a losing battle against these two. But they kept on refining their offerings, and today they fight head to head against these two. Their mid range is clean and leans towards being neutral. It is the high end that Pioneer excels in, delivering them with clarity that few can do so well.
5. Sony brings the same sound signature as all their other equipment. They add a bit of extra power at all budgets, making you believe it sounds 'better'. Using DCAC instead of Audyssey, they may lose a lot in terms of room correction, and may thus not be in the same league as the others.
6. Yamaha. Yamaha tires to separate themselves from the rest by offering two differentiators - their own calibration, and oodles of their own sound processing. Yamaha has two extremes - people who hate them and people who love them. If you like their sound processing, you will not like other AVRs. In addition, Yamaha UI is not all that friendly. In terms of sound, I would slot them somewhere between pleasant and harsh.
In terms of features, I would reckon Audyssey is need as is some Networking. And of course, capability to handle DTS-HD and Dolby True-HD. In terms of video processing, the choices are many, but I would prefer a simple pass through. With Blu-ray through a good player, there is no sense in upscaling. A good original DVD player through a Pioneer player looks superb without any processing. And, irrespective of what you do to a pirated DVD, it can never be improved.
Use these as pointers in your audition. Look for the way the AVRs handle high and low frequencies, dialogues, and lip syncing. If these are handled well, you have a winner.
Cheers
