Although i only purchased my DC30 a month ago, the tubes have already started giving me problems. The EF86 is extremely microphonic, and the rectifier tube also suffers heavy amounts of rattle. I know I could simply go back to my retailer but I figured now is as good a time to replace them with some tubes that won't be so problematic, and a selection that can hopefully also sweeten up/soften the highs of the amp. I plan to replace these tubes with either higher quality or NOS tubes. Seeing I use channel 2 exclusively, I figure its not worth replacing the 12ax7. However, I was looking to replace the EF86, 5ar4 (i think thats the recto tube) and the EL84s. I've read up on recommended tubes but I have a few questions. First off, I know the DC30 is notorious for burning through tubes, but are the preamps or power amp tubes most likely to go first? I'm alright with purchasing NOS tubes but If they will all burn out in 3 months I am definitely going to think twice. Would some NOS tubes be more beneficial? Would a NOS Mullard Longplate EF86 serve to improve the tone more than some NOS EL84's?