I have both a KAV500 and a Bryston 3B NRB. They both do bass very well, they both have a nice detailed top end, and they are the most different in the midrange. The Krell has a smoother sweeter midrange where the Bryston is a little more congested, confused and dry. I have heard 3B ST's and they are better than my NRB, but they still don't have a midrange "2 die 4". My suggestion would be to look for a used Rowland. The Model 1 is about $1500 used and kills the rest of what you mentioned. You'll probably wind up using it for the front L&R channels and the KAV500 for the rest. When you hear the depth of the soundstage in the Rowland and the holographic images it produces compared to the 2 dimensional soundstage in the Krell and Bryston, you will understand why I like the Rowland. Oh yeah, the midrange is "2 die 4" in the Rowland.
How would Krell & Bryston Amps Match
I have a krell kav 500, I am thinking of bridging it for fronts and center, and using a bryston 3 bst for rears , any opinions on how these 2 amps would match sonicly, my other choices for rears would be rotel or nad,