An awful lot of amps can be traced back to Fender or Marshall roots. Cleans are almost always universally Fender preamp derivatives, and distortions are usually Marshall-based. Even a lot of the uber-high gain amps are nothing more than a Marshall JCM800 with an extra triode stage thrown in for good measure - compare the schematics for a Mesa/Boogie Dual Rectifier, Soldano SLO100, Bogner Ecstacy and a JCM800 and it's easy to see where a lot of the designers' inspiration came from.