[bjs]

I owned a Behringer EP1500 and an A500. Both were exceptionally noisy (both signal noise in the audio spectrum and because of fan noise) and neither was anywhere near as powerful as advertised

and,

I measured the amps outputs using an o-scope. The A500 produced nearly 25% THD at rated output into a resistive load, and yes it did sound terribly noisy running full range...

Sounds like something is wrong with your A500s. I have 3. They have no fans and are therefore dead silent acoustically. They also have no noise electrically even with my ear next to the speaker. Agreed continuous power is down compared to rated specs (about 190watts versus 230watts into 4ohm load) but distortion stays under 0.1% up until it clips, this is into real world complex loads. My biggest concern would be build quality and QC but that's probably true of a lot of these amps.