My first 100 watt head was a Rivera Knucklehead Reverb KR100. Channel 1 was indeed a great clean channel providing an incredibly wide variety of clean tones from blackface to tweed using the push pull knobs. I always said the clean channel alone would be a great amp, and I did use it for Jazz gigs. One of the best Jazz tones I've ever had.
Channel 2 was voiced similar to a Marshall but not the same. I thought of it as Marshall mixed with Fender, Great gain tones for Blues to Classic Rock.
Channel 3 was the high gain channel and again seemed like a mix of Mesa and Fender more than just being a Mesa clone. Slipknot's Mick Thompson had one modified to be a signature amp that he used with Slipknot called the K Tre.
As wonderful as that amp is, I've had it for over a decade, I had two concerns: the master volume on channels 2&3 had to be above 3 in order to sound good and at that setting the volume was way too loud for anything other than playing live in a good sized venue. In order to compensate, players came up with "the effects loop trick" by setting the effects loop send and return knobs to the same setting somewhere below unity gain. That helped quite a bit but was only useful to a limited degree.
My other concern was the shared EQ for channels 2&3. There was no setting where both sounded their best and the best compromise left both sounding less than ideal. Since it was a MIDI amp I planned to EQ them with my Fractal FX8 with individual settings for both but I ended up going with a Sig:X and eventually a 1x12 combo instead of hauling around a 100 watt head and 2x12. Still, I love that amp and would highly recommend checking it out for anyone who is looking for a three channel 100 watt head.
My living room rig before I replaced the Knucklehead Reverb with a Fryette Deliverance D120. The 2x12 under the VHT cab is a Rivera Sub 2 500 watt 2x12 subwoofer.