I could not find 4 matching 12ax7 tubes yesterday. Here is what i came up with. 2 groove tubes 12ax7M and 2 groove tubes 12ax7R tubes. The russian tubes are the new ones with the sticker instead of the GT logo painted on. would they be a 12ax7R1,2,or3 version,or none of the above? So, if this was your amp (DSL50)what tubes would you use where? New set of GT E34LS with a 7 rating also. I've heard a lot of debate about marshalls 45ma bias recomendation, some say that's too hot. Any one have any experience with these tubes?