I have a lot of tubes lying around but I haven't been able to tell a big difference in tubes and positions in my ac30 amps. I have an ac30cc2x, Bruno ug30, z wreck that I want to retube. For power tubes I have went with mullards which I'm not happy with. The z wreck gets 7189s and I used to only use sovtek el84M tubes in everything else. I assume 7189 in everything or Ms are the best power options. What about preamp tubes? I am looks my for clean headroom w bass and chime. What is the significance of each tube in each position? And does v3 need to be balanced? I have used a lot of Jj stuff and Mullard or sovtek lps tubes but never found anything that sounded so great that I had to keep it that way. Any help?