Hey man, what tubes and different how? I'm thinking of retubing mine specifically to improve the M voice, just for fun.
Hey bud! The el84m (6p14p-ev) is a serious piece of electronic equipment- they are heavier and thicker than any other el84/6bq5/7189 or equivalent. Their tone is interesting- as compared to the original tubes the el84m has more clarity and a larger sound stage. I get my tone by cranking the Top Boost channel through an attenuator and dialing it down to low volumes, so that's why my original tubes cashed out so fast, and why Doug suggested these over-built beauts. When played by itself the amp might sound a little better with the original tubes since they seem to be a little smoother, but I think I prefer the el84m as it cuts through the mix better, and I mean really well, and no matter how high I crank the amp I can kinda hear the clean note behind every string. Excellent string to string clarity too- in the mix the el84m is just a winner. I plan to still pick up some of the Mesa branded tubes anyway just to be certain.
I recommend creeping up on some of those el84m though- they are actually vintage stout Russian gems at a great price considering. Let me know which way you go and your thoughts on what you end up with please!