how important is damping factor when looking at amp specs. i've heard that for s/n, when you get above 90 you cant really tell a difference. it it the same for DF when you get to 200+? is it important to crunch the numbers like this or will i be safe just buying a good brand of amp with the power i'm looking for?
You usually wouldn't notice a difference with a damping factor, most amps today far surpass that required to notice an audible difference. Damping does show quality of materials used, especially the transistors, so higher damping usually indicates more quality materials used in the amplifier, assuming it was rated correctly.
yeah I forgot to mention just skip to the part about damping on both those links. the rest is relative, but it's not needed unless you want to get a feel for how it all works together. I get a bit long-winded on the amp fundamentals article. It's a bit long.