Yes, I know there have been a million threads on this amp but I have a few questions I haven't seen answered. I just bought a used WT-400 for $500 that's in great condition (except for a loose DI level pot on back that will probably need to be replaced). I've had it running for a total of 6 or 7 hours (including a medium-volume rehearsal) and it's performed flawlessly-sounds great, good patching capability, fan stays off at solo practice level (a must for me). What I want to know is: 1) When did Eden make the "Low Noise" modification? I believe this involved turning the fan around to blow out instead of in (less noise) and rotating the toroid (same reason). Was anything else involved, and can this be done easily by a local tech or should I ship it to Eden if necessary? Mine's from Feb. 1998. 2)Is the extended warranty plan available on the Eden site worth it? What's their turn-around time for service? 3)Does changing the tube have much effect on tone? If so, what type do people recommend? 4)Anyone got a schematic they'd like to share? 5)Does it need spaces above/below when racked for heat dispersion? 6)Anyone got a bag and/or set of rack ears they'd like to sell? Overall I'm very impressed with the little unit. I was thinking of getting the WT-550 when it comes out but this does almost as much for half the price (used). Sounds heavenly with my new FBass BN5 and SWR SOB 1x15. I wish it had pre/post DI switch, Speakons, and a post-EQ 1/4" preamp out--but I'm not complaining. Also the built-in Eden fatness is taking a little getting used to but usually sounds very good. I don't think I'd buy a WT-400 new but I'd highly recommend a good-condition used one.