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
To be fair, the parts cost on all car brands are extremely high. And there's a reason for it. Car companies struggle to make a profit selling cars. There's a lot of competition, and not a huge markup on the cars themselves. Also, factor in the cost of the warranty and recalls.

Since they can't make a lot of money selling cars, they sell expensive parts instead. And they go where the money is; insurance companies. When a car is in an accident, it activates the insurance policy. The insurance company needs to buy parts to fix cars, and since they can afford whatever the cost of the parts are, so they charge high prices knowing they can get it.
I live on US soil, but lived in Europe prior. For me maintaining BMW is way simpler vs. Ford, Honda or Toyota. I order parts online and pay less than half vs. what shop charges for genuine ones. Electronic packages are made specifically for US market and US market needs jobs too. Mercedes Benz have even more sophisticated ones that fail for the same reason. A well built and reliable models don't reach US since they're not eligible to be imported here.
My garage:
2003 BMW Z4-roadster -- garaged and for pleasure -- got from salvage auction with theft recovery title -- Best Money Wasted!
2014 Subaru XV-Crosstrek -- daily driver.
Prior had 1997 BMW 318i convertible. Donated with 318kmi
Anyone can challenge Z4 with Ford Fusion?
Disclaimer:
I freelance at BMW repair shops on weekends at $50/hour. I'd normally finish job twice faster than AllData estimates so factually earn near $100 hourly. There's no other car or truck I want or interested to professionally maintain in this part of my career.
Many challenged me as I can't troubleshoot BMW without super-fancy professional scan tool, but I proved I could do that with just a test light just to impress shops right in front of manager's eyes during the interview.
"Many challenged me as I can't troubleshoot BMW without super-fancy professional scan tool, but I proved I could do that with just a test light just to impress shops right in front of manager's eyes during the interview."

What exactly did you do? You know I was kidding a bit before, but I'm really interested.