amp or preamp to extend upper end


I went from a fantastic little Krell integrated amp to a Musical Fidelity M6 amp and preamp. Found that the high end is a bit rounded off -- that amazing detail I had on the cheaper Krell is lost. My dealer said that the owner of Musical Fidelity designs his equipment for this sonic signature intentionally. Maybe I just got to used to an over-emphasized high end.

Question: would replacing the amp or preamp have a more noticeable impact on extending the upper range (assuming the new equipment can do so)? Any suggestions? Speakers are Vanderteen 3s.
evolving
...BMW always drives. One of the most perfectly engineered automobile and easiest in DIY maintenance.
"...BMW always drives. One of the most perfectly engineered automobile and easiest in DIY maintenance." Not sure about that last part. Witness my neighbor who just got stranded on the NJ Turnpike in his 328. Or another neighbor who just spent $5k tracking down an electrical problem in his X5. Electronics, electronics, electronics. The bane of most Euro cars, and uber expensive to fix. Love Bimmers and they're certainly better than most of the breed, but I think your statement pertains more to a 60s/70s VW Bug than a late model BMW.
I'm confident on all models upto 2007. Parts are not overkill and work on any repair is faster than in any Toyota or Honda.
Expensive maintenance prices only for the fact having european luxury car.
The German's used to make good cars, but they've been going downhill fast. They're so complicated now, its a miracle they even start to begin with. German's aren't the only ones, but they are the worst.