I just retubed my Carr Mercury with some pleasing results. I thought my speaker was farting out on the low end so I plugged it into a couple of other 8 ohm cabinets I have and the problem was still there. I've been stocking up on some NOS tube goodies the past year, so I pulled the box out of the drawer and started digging. Ended up swapping out (2) GT 12X7's, a GT12AT7, and a JJ EL34 with some dusty antiques that just kick ass. After 3 hours of swapping in and out, the final line up is : 50's RCA blackplate 12AX7 , JAN Phillips 12AT7, Brimar 12AX7, and a Amperex EL 34 Holland made w/ double D getters. The farty bass is gone and has been replaced with a round, crisp, 3d tone. Cranking the clean setting with the renewed reverb dimed made the 007 theme sound like a remastered DVD through surround sound. The overdrive setting really got warmer and smoother, yielded some great "texas flood" type tones and seemed more responsive with way less mud. On the highest gain setting I was in that "controlled feedback" zone, ripping through some Trower like leads, working the Wah and being driven into new sonic territory that just wasn't there a few hours before. Bottom line, the NOS tubes do have that mojo tone we all strive for. It took some time, objective listening,and money, but in the end, its a cool way to spend a day off.