Well, it has been some time, and I have tried all sorts of 6SN7 and 12AU7 combinations to get the sound the suits me best using the MP3 and M60s. I have tried Sylvania and RCA GT, GTAs, and GTBs on the amp. The best combination for me was two RCA GTBs in the front and two Sylvania GTBs in the rear with GE 6AS7s from Roger Modjeski. In the preamp, the best sound for was the RCA Cleartops with RCA GT Greyglass, but frankly all the RCA variations sounded good to me and I preferred them to the Sylvnias in the preamp - that might have to do with the fact that I am using Merlin VSMs and the "warmth" of the RCAs just suits the speakers, especially the tweeter, better than the tipped Sylvanias. That being said the system sounded mighty good no matter what I put in there and I would say triode balance and quiet tubes are as, if not more, important, than the brand I chose. Once that is taken care of, the hairsplitting and preferences can take place. I think I'm set for now, but I do think I've got the Atma-sphere setup sounding as good as I can get it, BUT, tomorrow or the day after, I will receive the Amperex 12AU7s, we'll see how they do compared to the Cleartop I have in the MP3 and the RCA Blackplate 12au7s. Thanks for all the advice. I just wanted to add that in my search for tubes (for my Music Reference RM9SEs as well) that you can't do much better than working with Roger Modjeski, Andy at VTS, Brent Jesse, Jim McShane, and Jim Sutter. All fine gentleman, knowledgeable, an perhaps most importantly honest.