i believe the H has more gain. if i remember correctly from my research - they are two different designs...with the non- H and earlier H's being different.
I owned an H for a few months. Loud indeed. I sold it for cash not because it didn't rock. It did. I played the cabinet for it last night with an ampeg. holy beejeebus it's loud.
good luck! I still get emails asking for mine and i posted it many moons ago.
It's a guitar amp that is loud and has lots of gain. It is also heavy too!!!!!!!
It has a master volume and a low and high gain input. Built like a tank and it is heavy and loud. Sometimes called a poor mans Marshall. I recently sold mine.
I don't have to have the H version, near as I can tell there far more harder to find. I remember when they were still making these things and trying to get rid of them you could pic them up for like $350 in AMS clearence section....