This is what Amir has to say about the two of them:
"Conclusions
The Behringer A800 does what pro amps try to do: provide solid, middle-of-the-road distortion and noise with tons of power in a quiet and light package for little money. The design is stable and better than the A500. As such, I can recommend the A800 as an everyday amplifier."
Why 15 Hz cut off would be something bad I don't understand. It's probably only good to cut out things that you can't hear anyway, as long as the FR goes down to 20 Hz (pancake flat without roll-off to 20 Hz, that is).
From another forum about it:
"In order to eliminate LF "noise" such as air conditioning rumble on the recording, or TT rumble when playing an LP, many electronic units do have a sharp filter below 20 Hz. The idea is that this signal wastes amplifier power, and drives loudspeaker cones in and out, which you can't hear but which causes distortion of higher frequencies that you can hear."
if an amps frequency response are spec'd out to be between 20hz to 20khz, will it pass information above and below those numbers?For instance will it pa...
forum.audiogon.com
Fragile, you say. At least I know one person whose A800 broke after a year of use. If it was an exception, if he was unlucky, I don't know. The A800 is probably,hopefully a reliable amplifier for home HiFi use.
If it had been badly constructed then one would most certainly have read about it. There is a tendency to create threads about things that are poorly constructed. An example of that:
Poll for PA5 owners to report product defects. Discussion for any solutions. I think it would be useful to get a handle on some numbers to estimate just how wide spread the issues are. Addendum: Here is Topping's response to the PA5 issues...
audiosciencereview.com