1. I think the most interesting difference between separates and the receivers I've owned is at low volumes where there is no question but that the amp section of an Onkyo 797 is adequate. Why then do some outboard amps sound better?

I have a friend who 'upgraded' from his Denon to the 200 w Outlaw monoblocks. The sound quality did NOT improve. I'd say the sound quality got worse. (I like Outlaw products, have nothing against them and wish them well - I've owned some myself which I loved - not the monoblocks).

On the other hand, I have a friend who upgraded from a Denon receiver to Parasound Halo separates. Big difference.

My Big Brute Yamaha M80s made a big difference.

As to pmbuko's point, as to whether the sound stage is huge because my surround speakers are passively resonating or not, I dunno - I'm certain that the effect is caused by the presence of those speakers. If not, hey folks, we don't no stinkin surround and back speakers, we just need some ventrioquist drivers in our TV box.

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.