Hey, I have owned my Hughes & Kettner Puretone 25w for several weeks now. Considering I purcahsed the amp used, I don't the life of the tubes. I'm getting them replaced, as I can hear the symptoms of worn tubes. Here is my dilema- the certified H&K amp technician is a 2 1/2 hour drive. Their expected turnaround is three weeks. They recommend Tube Amp Doctor / EL34B - STR and 12AX7A preamps. Considering the wait time, I am considering looking elsewhere. Bob at Eurotubes recomended a matched pair of JJ EL84's and two ECC83S's (one balanced for the Phase splitter). I don't feel comfortable making the change myself, and don't have a local amp tech that I trust. I opened the phone book and made a ton of calls. Through my research, I came back to a tech within a hour drive. He came with several referrals. I spoke with the guy, and he seemed fairly knowledgeable. He was surprised that the amp was only 25w, and didn't take EL84's. After some conversation, he recomended Svetlana EL34's. His wait time is 1 week (or 10 days with the holiday). I love the stock H&K Puretone sound, and want to maintain or improve upon it. Most of all, I love the clearness, bottom end, and "swirl". Maybe that is a Vox "shimmery" sound with more thickness / bass. What is your recomended course of action? Myles, I've read through your guide and the JJ's seem OK, and Svetlana seem to fair well. I haven't read a review on the EL34B - STR, but would be more than happy to keep the stock sound.