I started my new and long debated project this month based on the Telefunken RS291 in S.E. in triode. The schematics are identical to the famous RCA 45 tube. The 291 needs a bit more voltage on the anode and 10K output transformers. This'll be fun.
Below here is my final version of my Exodus I pre amp.
Setup: Philips AX1 mercury rectifier, Tronal VR105 stabilizers x2, Time relais tube 60 sec delay for the AX1 and the Philco 27 tubes at the front.