I've been an Audio Research fan for many years. I never owned an Audio Research amp, because when I was buying an amp about 25 years ago, the Audio Research amps sounded bloated. I don't think they do anymore. Which means that Audio Research did a bunch of audio research in the meantime.
I have owned a number of Audio Research preamps. Although they're not amps, they will make my point. I owned a Reference 2 and Reference 3 preamp. The Ref 3 was a lot better. It had a much cleaner sound.
My point is this: I can't simply take on faith that somebody writing in this forum is a better engineer than the folks at Audio Research. So, if they keep learning and improving, I would have to assume that an amp of your design would also have shortcomings, and probably far worse shortcomings that the pros at high-end manufacturers.
It's like guys who buy drivers and build their own cabinets and swoon at the sound the way a father does at his newborn. If a company like Sonus Faber takes years and years to keep perfecting the integration of their drivers and cabinets, does that count for nothing? I own a Hovland Radia amp that I love, and Bob Hovland said it took him 25 years to design and build his only solid state amp. And he was a top-rate engineer.
So, I don't take it on faith that high prices on audio equipment are not worth it. Or that a guy who understands electronics could build a better amp. Although, I do believe that if you build your own amp, you will believe it's better. And in that case, maybe it's worth it.