Does anybody know a good sight that explains what all the numbers mean...say on the spec sheet of an amp or DVD/CD player. For example, on a DVD player, what does the audio signal to noise ratio mean, and is higher or lower better? Or on an amp, what is total harmonic distortion (I know this, but I'm just using this as an example)? Or say on a CD player, what does the "dynamic range" mean and is it better to be lower or higher? Sorry to sound like an idiot, but I need to brush up on all this stuff if I'm shopping for new gear. hehe

Thanks.