No way you can run that amp dimed. Prolly hearing the speakers overdrive/compress.
For giggles I hooked up my Shuttle 9.0 just into my 8 ohm SWR Golight 2x10 tonight and played for a while. I would not dare dime the master. I could only imagine how bad that would sound, with things on the verge of flying apart.
First I was impressed with how loud it was with the master half way up and both gain/levels at noon. I set the low boost and mid scoop on and pushed it on up some in volume. It was way louder with more bottom than my 72 Ampeg V4B dimed into my 4 ohm Golight 4x10. I sat there an ABed both back and fourth. I played it for a while with the mid scoop off and left the low boost in.
All I can say is I am so fortunate to have this Amp. The tube feel of it alone is worth the entrance fee, the extra grunt is just icing on the cake.
Who was it came along and said the latest flavor of the month amp sounded more tubey? I think theys is smokin motta. This 9.0 sounds more like a tube amp than my tube amp.

Just because the latest flavor has a knob that says tube on it means nothing but little fishies swimming right behind. Hope he don't make a right turn.
I am just very fortunate to have run across this little bugger.
Genz Benz gets the Red Planet Lifetime Achievement Award for Best Product of the Millennia.