High power amp reccomendations, airy highs a must

To answer a few questions ... I'm driving PSB Stratus Silver i speakers via Goertz MI2 bi wire speaker cables. Pre-pro is a Reference B&K, front end is a Lexicon RT-20 with 7 nines solid silver interconnects.
I consider my system pretty much neutral to my ears with very few minor sins, if any. Only thing I'd like to see improved is a little air in the highs and a little more taut and controlled bass/mid-bass. This has been well documented to be the hallmark of the Stratus speakers, but changing them is not an option, as I have heard NO speaker that can play as loud, sound as real on drums and stay musical at any level .... at least that I can afford. I'm fairly sure a change to a more resolving power amp with a high level of bass control and airy, extended highs will get me that last little bit. Problem is: My budget maxes out at $2000. Used will probably be a must.
I've also considered replacing the tweeters with a world class tweeter from Scan, but have NO IDEA how it would mate with the rest of my speakers in the cabinets.

Bryston 4BSST

Yeah ... a Bryston 4BSST was a HIGHLY looked amp I considered, but they are really too pricey for my budget. Most things I have read called the Bel Canto gear leaning to the warm and musical side, which I already have. Haven't heard McCormack's newer DNA Series though, and Belles looks interesting as well. Thanks for the reccomendations.

Oh yeah ... Here's the funny part: I'm a true audophile who listens mostly to complex, hard rock. Think Tool, Korn, ect .... While most audiophiles will scorn this musical taste, I find systems challenged JUST AS MUCH trying to resolve this music as I find them trying to resolve Classical Symphonies.
Making Dynamics and clarity a must ... but running away from anything sounding cold and etched, as listener fatigue will be almost instant.

For approx $2100 you can get a pair of Bel canto Ref 1000 Mk.1 monoblocks. These are very good amps that are highly musical and do not get easily confused on harmonically complex material during intense passages. Ihave used the Mk.2 version on my power hungry Vienna Mahler speakers and have written a review on Positive Feedback:
http://www.positive-feedback.com/Issue43/bel_canto_ref1000.htm