Point of order: the best amp is not 'bright', 'warm', or any other characterization of distortion. It will be relatively distortion free, or silent.
For instance, if you look for a Total Harmonic Distortion (THD) rating of <.05% (or at most <0.1%) over a frequency range of say 10hz to 50khz, you will have found one.
Prices can vary from a couple hundred (Hafler DH-200, 220); to thousands aproaching six digits (Jeff Rolands multi channel); with Rotel, ATI, Muse, and Bryson, filling the gap between.
So, you want no sound from the amp, and perferrably only what made it onto the source material coming from your speakers. That is, 'true to the original' as a philosophy. Then you can select sonically superior CDs (or whatever) and be shocking close to real, live, sound. Tweaking speaker setup becomes productive at this level.
Of course the many, many, poorly produced albums will then sound just terrible. But at least you will not be mistaking the offence as a quality of some component of your system. Nor will you be indulging in the cable, room treatment (and other tweaks) very costly and frustrating madness.
And if you are wise, you will not attempt to compensate that terrible sound with some opposite distortion in some other component. Madness. The magazine reviewer 'Connoisseurs of Coloration' notwithstanding :-)
Try it, it is worth it.
Check out http://www.linkwitzlab.com/ where you will find a wealth of info on various aspects of audio truth, and a list of proven sonically superior recordings that can be used as a reference in discerning components.