If you're happy with the Musical Fidelity sound, consider bi-amping as a cost-effective option that will maintain the system's sound. I had a pair of A3cr power amps controlled by the A3cr pre driving B&W 602. Though the 602 is clearly not in the same league as the 805, which I considered, the extra dynamic headroom from two amps made a wonderful difference. The the system had shattering dynamics. My experience suggests that B&W can eat a lot of clean power. I also found the MF - B&W pairing worked very well.
Though I have moved to other speakers, I now have the Krell KAV 300iL powering the stereo. The 602 are still sitting around, and I hooked them up to the Krell for kicks. I did not find the partnering objectionable, but I don't find Krell to sound bright, either.
It could be the case that you cannot drop a Krell amp into the system and judge immediately. The Krell's famous iron grip, high current, push-pull, fully balanced design further breaks in the moving elements of a speaker. After this second speaker break in completes, the pairing may sound better.
I have no experience with Classe products.