I actually bought the HA4700 as a distribution amp for vocal monitoring during live performance. The first one I got was a lemon - it had a constant hiss in one channel on the left side. I brought it back and got another one. The salesman did mention that he has seen this more with Behringer than other brands.
It is installed at a club for live performance and I have never used it for any other purpose - so while using it, there is music coming out of the FOH speakers, rear monitor speakers (for those who prefer speakers instead of head gear, and subwoofer.
It serves it purpose and it serves it well.
I have no comment on using it as a hi-fi listening device (I'm using a FiiO E6 at this moment).
It is loud, clear, powerful, and it is able to pump a stereo mix to 4 independent channels plus each channel can mix in their own channel if they want - invariably this is that persons individual performance and some of us like to make it louder in the monitor mix.
I hear no hum - and if there was hiss, I couldn't hear it since the house speakers are always on the same time.
When I've had the chance to compare a Behringer model to the box that inspired it, I invariably favor the original inspiration. But also at the same time, the inspiration model costs 2x-5x more - but at the same time, the performance of the Behringer is not 2x-5x worse than the inspiration - it is close - and when price is an object, I'll opt for the Behringer.
For the sound system at the club, the patrons do not care about ultimate hi-fi sound. They are usually more interested in something else than just the music playing at the club.
But for my own recording purposes outside of the club, I have chosen the inspiration models rather than Behringer (vocal strip, mixer, enhancer, cans, microphones). However, this is also not for hi-fi listening.