Just picked up the 6534+ today. Going to do some A/B tests against my friend's 6505+ so we can all hear the difference between these two amps!
Since it's a relatively new model there really aren't that many straight A/B comparison clips out there, so I thought I'd do the world a favour and make one.
"In the room" the 6534 already wins, hands down. So much more full sounding, with a huge low end and rich mid grunt. But mic'd up and "in the mix" will probably be a different story.