In amp, and speaker choice, as for listening and evaluating, unless you have medical hearing loss, many of us can tell the difference, it's just that we don't know how to do so, so, we end up buying what pleases us most.
Now, for that truly very few (avoiding audio foolery garbage), since you don't know the what original instruments supposed to sound like, here is a good method to judge, though you require both the amp and speaker in the equation:
Pick a properly uncompressed studio recorded song with natural vocals without reverb or echo added. If the vocalist doesn't sound like the are there in front of you,
not a vocalist on a mic and speaker, I mean there, a physical human being, without a microphone, no speakers, a presence/essence you can feel in the room with you. At all volume settings. Be honest with yourself here, you should always be comparing what you hear to real life, NEVER compare hardware A to hardware B. Do this right and you picked winning hardware. Affordable solutions to this refinement do exist, however, it takes someone experienced in the business, with access and tests of many hardware and they are not out to rip you off to help you find such quality equipment.
Personally, It was recommended to me to purchase a Belles OCM 500 amp. I happy and will never will sell it. Though rated 0.1hz to 20Khz, I measured mine flat to 100KHz at full power. 250w/channel into 8 ohm, safe driving full load into 4 ohm. Some come equipped as mono-blocks with 1kw output peak. It is built like a tank and I don't expect it to ever die.
A used one exists here:
http://www.canuckaudiomart.com/details/649201738-belles-ocm-500-soloist-amplifier/A FN steal at 600$ cdn.
Some finer specs...
http://www.diyaudio.com/forums/swap-meet/205903-fs-ocm-500-david-belles-200wpc-amp-beast.htmlDarn, if it weren't for the shipping and that I'm lacking a pre-amp with balanced outputs, (it weighs like a concrete cinder block), I would buy this one and use it with mine as 2x 1Kw mono blocks...