I am a relative newbie to tubes. I bought my first tube amp, a Rogue Audio Cronus Magnum II, about three months ago. I absolutely love this integrated amp and plan to keep,it for a long, long time. I had read some about tube rolling, but decided to live with the stock tubes for a while to become acquainted with it. Well, the rolling bug bit last week and I decided it was time to "go exploring." As can be seen in the picture below, the amp has 4 KT120 tubes, 3 12au7 tubes, and 2 12ax7's. FYI, I am only interested in rolling the 12au7's & 12ax7's. I contacted Rogue for suggestions and received a very quick response from Bill (GREAT customer service BTW). He said to begin with the center 12au7 because that is the preamp tube and will have the most impact on the sound. He told me that his advic is simple. If you want more warmth, got with Mullards. If you want more detail, go with Telefunken. If you want something in between, go with RCA Clear Top. BTW, the stock tubes are basic JJ. Since I always lean toward more detail, I decided to start with Telefunken. So, I orders a Telefunken Black Diamond 12au7. Being naive about tubes (and admittedly not having researched things thoroughly) I did not realize that this was a reissue and made by JJ. Lesson learned. I figured I would give it a try and see what happens. It arrived today so I popped it in, warmed up the amp, checked the bias on the output tubes (it was time), and gave it a whirl. I used my favorite test album, a vinyl version of Dire Straits' Love Over Gold. Dropped the needle and...WOW! This tube sounded great! Crisp highs, improved mids, and tight base. Overall, more dynamic. Pleasantly surprised and pleased. I am going to live with this one for a while, but want to try out a few more before replacing more than just the preamp tube. So, my question is what reasonably priced ($100ish or less) tubes would you suggest that I try? Thanks for your input.