Quote Originally Posted by Macca View Post
looks good but nothing needs hundreds of hours of run in. I don't know why manufacturers say that stuff, other than it's expected of them I suppose.
Probably a 'get out' by the manufacturers. "I bought this amplifier, and I find myself rather underwhelmed by it". "Have no worry sir, they do need a few hundred hours to run in, after which you'll be much happier with the sound". By which time it'll be too late to take it back and change it.

More likely it's the listener's ears that need time to get used to it.