Greetings,.. For give me if this has been discussed before. With all of the different brand of preamp tubes out there,do they really make a dramatic difference in ones tone? Or , do they just make the amp work as designed? With all of the reviews out there regarding preamp tubes, ppl say " wow! made a huge difference in V1", or "this one works great as a phase inverter V5" or "this one is great for this or that". I have a MKIIC+ and have been tube swapping for yrs. .Its hard deciding on wht tube to buy just to experiment with and costly, perhaps only to be dissappointed. Wudn't it be nice if tube stores wud send you a platter of various tubes that you cud try before you buy? I still need to know that if a socket calls for a 12ax7, will any 12ax7 work? I totally understand bout noise and microphonics in v1. And, some ARE better than others , but what about tone and the sound that u are striving for? Granted, I put a 12au7 instead of a 12ax7 in my V1 and wow! how shitty it sounded!. The socket calls for a 12ax7, is that why? Wow, maybe I answered my own question..... What tube wud u suggest for my V1 ? I tried GT, Sovtec. Currently using Mesa's SPax7 w/ the black wrap. I just feel as tho that there is sumthin out there that will unleash my amp. RFT's, Tung-Sol's..... on and on.... Hope to hear from someone who has been down this road. Blessings. James