There is an old thread on tube rolling for this amp on the 2-channel forum, but it's hard to tell what tubes forks ended up with. I just picked up a used 401HR on Agon that came with the stock tubes (EH 6CG7 on the inside and Sovtek 6N30pi on the outside). It's not a bad pairing, but I would love to hear from current or former owners on their favorites. I have tried a few 12AU7s on the outside (RCA cleartop was best), but I'm not sure that I prefer them to the stock tubes. Do NOS 6CG7s make a difference? Favorite tubes on the outside?