a good quality amplifier does only one thing: make the signal stronger. that's all.

as regards comparative tests, the first thing to make sure of is that the amps MUST be adjusted to put out the same exact voltage with a given sine wave signal. a voltmeter must be used for that.

the brain is very finicky for SPL, but it has a very short memory.

See: http://www.blu-ray.com/community/gallery.php?member=Gelli
or: Axiom Gallery