Rogue Cronus Magnum 2 tube rolling

The Mullards are my favorite tube as well.

The 12AU7 driver tubes make a larger difference in sound than do the 12AX7 phase splitters in my experience and according to Mark O'Brien of Rogue. 

My preference is for NOS Mullard CV4003s. I use an RT 6189 in the pre-amp spot and either NOS Mullards or RCA black-plates in the phase splitter positions.

Funny how we got different answers from Rogue. I was told that the 12au7 driver tubes made the else impact.   In anycase, unfortunately I sold the CM2 and bought a solid state amp.