Tubes aren't for everyone but for some...tubes are everything. I found this very sweet sounding Golden Tube SE-40 that has been fully upgraded by Sonic Craft with their SE40REL+ upgrade. These amps were notorious for sounding sweet and failing; hence the upgrade performed by Sonic Craft. Now the guy i bought it from had a tube go bad so he put a stock tube in its place. Same tube but different brand. These are the power tubes and don't effect the sound tbh. I ordered a matching replacement though which arrives Monday. The tubes that do change the sound are the 6SN7 and I have a couple of shuguang treasure cv181-z tubes (matched pair from one of my other amps) to pop in. That tube sounds amazing. It is pretty much a drop in for 6SN7. I will of course bias all the tubes once installed. I'm going to run these Tung Sols for awhile though. Amp has shocked me. For a tube amp it is the most resolving, detailed amp I have heard. Loads of openness, wide sound stage, thick mids, detailed highs and solid lows. This has been an ear opening experience. I'm no stranger to tubes but this amp has surprised me. Feeding a set of Hsu Research MB-1 mkII's and a Velodyne CT-150. Simply fantastic ear love. Using a Schiit SYS passive preamp to handle gain control. It's the big tube amp to the right in picture.