Great clean channel but good luck getting any clarity on the overdrive channels. The gain channels are very dependent on the presence setting, which is very hard to tame. It goes from very dark to way too bright without much in between.
Great amp and features on paper - I had one and worked with it for a while. Had the midi hooked up and all but could not dial in a high gain tone with clarity no matter what.
Great cleans though!
I think its a great amp for the price and its incredibly versatile. The master volume does work as Vai describes, along with having 3 output levels. I use mine with the older 100watt Green Back legacy cabinet, so generally keep the amp at the 50watt setting. Recorded this on it.