I believe the Mark III uses 6L6 power tubes which put out more power than EL34's. 2 6L6's will put out around 60 watts, and 4 will do between 100-120. It also depends on how the power section is set up, I believe. I used to have a PV Triple XXX head that used 4 6L6's and was rated at 120 watts. I read a review of it from an amp modder, and he said that the one he had put out 190 watts at the clipping stage. So, just because an amp is labeled at say 100 watts, doesn't mean that that is exactly what it puts out. For more info than that, you'll have to see our resident "Gear Guru" Lats. :D