This is a fine piece of headphone amplifier for live monitoring purposes. I've used both auxiliary and main inputs, stereo and mono.

The sound is, compared to the mixer's headphone out, just a little bit degraded. However it is totally good enough for monitoring purposes and one cannot really tell the difference on a live situtation.

I like the fact that it has a total of six outputs, all of them having aux or main inputs. The EQ (bass/treble knobs) works well enough.

I don't like the knobs on the front panel - some of them are just a bit misaligned when centered. Some of them also feel a bit loose. Handling the volume/EQ/input mix is a bit cumbersome as the knobs are small and located very near each other. However in a 1U device with six outputs it is inevitable. Another this I don't like is that when the input mix knob is turned all the way to the Aux side, Main feed still leaks through to the headphones just a little bit. It is not really an issue in live situtations, but it's there anyway.

I have this integrated in a 5U rack case with an Allen&Heath Qu-Pac. It is a very nice addition to the mixer as it has three stereo outs plus four mono outs for monitoring.