There is a particular company in Australia sir, called Deqx. They claim that the highest distortion in a audio chain occurs during the mechanical conversion of the audio signal from say a electric output from a amp converting to mechanical energy at the transducer in a driver in a speaker. And I think I will go with that. I've tried a lot of amps, and never found them to be a bottle neck, as long as the power / current was sufficient. Though of course their presentation was different, amd what I considered poison, could be the next guys nectar. So I still feel, the biggest difference that one can get in their sound, is by upgrading their speakers, and not just amplification. And there is a other stream of thought that Linn advocates, which is source first. What is lost at the source , can never be recovered.