Well, here are my short comments on tube rolling so far. I have tried the Mullard CV4004 and the Amperex 7316. Both very expensive tubes. I'll probably keep them but I figured I could sell them if I don't like them (but, I do like them, oh yes). Finally, one doesn't really need to tube roll this amp as it sounds great with the stock tubes.
Mullard CV4004/12AX7: If you could draw a picture of the sound, then the Primaluna prior to this tube would have fuzzy edges. The edges are now clear and precise. Sexy? Yep. Kevin Deal's recommendation on this tube is right on point. I love the tonality of this tube. Most noticeable was what it did to the bass...so much more to hear from the bass.
Amperex 7316/12AU7: Still way to early for comments but I do notice that pairing this tube with the Mullards leads to a tighter sound with more punch. The bass sounds lower and fuller to me but with the same amount of definition I gained from the Mullard (good!). Soundstage seems moved back a little bit. Both tubes made the soundstage less forward. I definitely hear a lot more 'energy' in the music than with the stock Chinese tubes (also good!). I need to play this tube a bit more to get a real impression, however.
Next up will be some less expensive current production tubes.
I listened to Tim Buckley - 'Happy/Sad', Joni Mitchell - 'Blue', Air - 'Talkie Walkie', Echo & the Bunnymen - 'Crocodiles', Bill Evans 'Explorations' SACD, Sarah Vaughn - 'Sarah Vaughn', and many others.