I love mine, and can set it to do pretty much anything (from hardcore Western twang to Grant Green jazz. IF you are playing it REALLY loud, the single 12" will sound crappy and bassy.
I would suggest that over 5.5-6 on the clean channel is too loud for that amp, and you lose the sweet spot.
The dirty (green) channel is about the same. The first gain channel is good, but I really wouldn't go above about a 30% on the drive and keep master below 6 or 7.
The red overdrive channel is completely useless for that amp (at least IMO). It sounds dry, overcompressed, and very 80's solid state.
You may have a tech issue or just an issue on how to dial in the tone. The HRD can be a bit tricky to dial in sometimes, and if you are playing with a REALLY loud band, it may not be the best amp.
The speaker/ power config is pretty inefficient which is why it sounds so great IMO.