I haven't done much rolling with my MP-1, but I'm using a Raytheon 6SN7 in the forward position(differential amplifier where all LS gain is performed), a matched pair of 6SN7EH in the circlotron, and 6SN7EH in CCS. IMO the latest EH production sounds clear, extended, & musical. The front 6SN7 is a good place to experiment with NOS tonality. In the phono section Mullard 12AT7(selected for low noise by Jim Mcshane), improvement upon the stock Chinese tubes both in quietness & sonics. The first two 12AT7s in the phono section circuit are in parallel, forming together the top half of a cascode with the third tube. When rolling the phono stage, you would probably want to replace the first two 12AT7s with the same type of low-noise NOS tube.
Recommended 12au7/5814s for Atma-sphere MP-3
I'm told these are the tubes that make the most difference in the MP-3; I have Sylvania 6sn7GTBs for those tubes in the unit. I think that how a tube sounds has a lot to do with the circuit that it is in, so I would like to hear from those that have rolled the 12au7 tubes in this particular unit; although I also welcome general comments on the 12au7/5814 breed. I have RCA Clear Tops, Siemens 5814s, RCA Black Plate 5814s, RFT 12au7, and RT 5814s, and Tungsol 5814s - I haven't started rolling yet; I have the Siemens in the unit and it seems to be very clear and spacious, but I'd like to know what other flavors I can expect with some alternatives. Thank you.