I have each of these and am trying to figure out which one to sell. I also have an old 70 SVT and a recently purchased peavey Classic 400. I've had the 400+ for a while and in my last band used my SVT and I think I am liking an svt sound more these days and figure the svt II sounds pretty similar and I wouldn't have to worry about moving my original svt around. Internally, I think the ampeg is built better. The circuit boards are thicker and are much easier to remove to work on if needed. I replaced the filter caps on the mesa a while ago and the pads lift very easily on mesa's circuit boards. The mesa I could replace if wanted but the ampeg isn't made anymore. I guess I want thoughts from others who may have used both. Obviously, I am leaning towards the ampeg but just want to hear opinions. Thanks.