Mine came with mullard el34s (and my previous amp was a 6l6) and they sounds so good I haven't been in any rush to take them out and try the sovtek 5881's I have lying around. They sound fantastic, even on the dlx. I don't know if it's just the amp or the tubes though, but I'm damn happy The highs are not shrill but still clear, the bass is not boomy at all but still doesn't feel stiffl, and the mids just have something I can't put my finger on, but it's great. Very smooth without being the least bit bland. It's like all the frequencies blend in well with each other, more like a continuum rather than trying to match 3 different faders in and out to get that right combination.