I almost went locally with a pair of Russian Groove Tube 6v6gt's for my M102. Guitar Center wanted $55 for the set though. The Chinese Groove Tubes were the cheapest, I think he said 38.00 for the pair. I've liked Groove Tubes in guitar amps too. I replaced a stock Marshall pre amp tube with a GT 12AX7 and it made a big difference. I got a brighter tone, more clean headroom and more gain. It gave me nice sparkly highs that I really like, especially on my Marshall. I decided to go with the Tonewheel General Hospital and get their Electro Harmonix 6v6gt's for 35.00 for the pair, and also put in the order for the tonewheel generator oil (vintage era). This way I can establish an account with them. I don't know how the EH's compare with the other brands, but if that's what they recommend, I'll sure they'll be fine. GC told me too that once I put in a new tube, if it's a bad tube they won't replace it. The surprised me. Every one in a while, a bad tube gets sold, and seems to be a growing problem from what I here. JJ tubes, which are normally very good tubes had a bad batch go out and quite a few guitar players were complaining that they weren't lasting long at all, and some blew right away. I think Tonewheel General Hospital will be more forgiving, I could be wrong. Hopefully I'll get the order in by the weekend so I can see how this M102 is going to do. I haven't even checked the tone wheels yet, I thought it'd be better until I have the oil ready to go.