Andy Bowman really knows tubes. I have gone to him for my 12au7's for my Rogue Pharaoh integrated. My opinion, if your speakers are on the "sharp side 'o cheddar" in the upper mids to low treble region go with the Mullards. If your speakers are a bit subdued or slightly rolled off in the treble, go with Amperex. I feel Rogue is a good choice. Very good sound for a reasonable amount of money. You should notice a good step up in SQ replacing the stock JJ tubes in the preamp section.
Cheers.
Tim
Cheers.
Tim