I used a Texas Heat with a Mark IV and really liked it. With my Express 5:25 I have been using a Cannabis Rex and really like it. I have to say, on an older Mesa Studio .22 that I used to own, the amp was OK as practice amp, but not enough to be used with a band. I opted to put in an Eminence Wizard, and bingo....amp is a killer grab and go even with a loud drummer. The Wizard is rated at 103db. To gain an extra 3db it requires a more efficient speaker or a doubling of power. Since the Studio .22 is ~20w, (probably more like 18w) going from a speaker of 97db to one that is 103db, is like doubling power twice, (18w amp to 36w and then again to ~70w). Bottom line, with the more efficient speaker, it gets louder and I found the voicing was great for that amp and made it loud enough to keep up with a 5 piece rock band. I suspect the Wizard might be good in the Express, too. FYI - a V30 efficiency is 100db and a Texas Heat is 99.6db. So they will be the same loudness, just voiced different. Cannabis Rex is 101.8 and Wizard is 102.8db.
