AV Receiver good enough for high end audio?

Of course not.

No
Not one made currently.
Some early ones were reportedly good but don't have the mandatory features you would need.
Let me add that. I have heard the big AV manufacturers claim outstanding audio but it seems they alone actually believe it. The modern hi fi cottage/boutique 2 channel guys that go into mulichannel imperil their fingernail grip on survival. At one recent Retailer/Manufacturer demo for my audio group. The rep for a successful firm was asked about multichannel and retorted with a "we just can't afford 50 or 60 programmers" developing price plummeting obsolescence every few months. And he added consumers simply will not buy dated technology in this area. He then recited a list of companies who had gone under or nearly were destroyed trying to enter the frey.

THE BEST A/V RECEIVER I EVER HEARD, AND I'VE HEARD A LOT OF THEM UNFORTUNATELY, WAS THE LEXICON RV-8. IT WAS ESSENTIALLY THEIR SEVEN CHANNEL POWER AMP AND THE MC-8 PRE/PRO IN ONE CASE. I ACTUALLY GOT TO HEAR IT DIRECTLY AGAINST THOSE VERY SEPARATES AND THERE WAS NO DIFFERENCE, SOUND WISE ,THAT I COULD HEAR. Having said that I still don't think that this receiver would hold it's own against high end two channel separates in the same price range, but neither would any separate pre/pro power amp combos I've heard either. One other thing, lexicon has taken a serious hit to their rep recently when it was discovered that they took a five hundred dollar blu=ray player, put it it one of their cases virtually un-changed, and then decided to charge eight times as much for it.

Sorry about the all caps in the first part of my response. My daughter always leaves the caps lock on and I didn't notice it until some way into my response, and I didn't feel like deleting it and starting again.

i thought you were trying to be heard ;)

I love my Rotel RSX-1057 AVR boosted by a Rotel RMB-1075 120watt/ch multi-channel amp. I don't use the tuner but play CDs, SACDs, DVDs, and Blu-ray DVDs. Sound is fabulous as far as I'm concerned. For music, Rotel is one of the best values for the money (mid-fi) IMO. I really don't need the receiver itself since I'm not using the tuner or the amp inside the AVR but it's what I started with. I used the AVR on its own first (75 watts/ch into 8 ohms all channels driven) and that was fine. I then upgraded to the B&W 683 loudspeakers and wanted to drive them with more power. NAD would be another great choice.