From what I read around here on talkbass, I get the impression that lots of people swap out the tubes in their tube heads and rebias them accordingly to get "that" sound. Has anybody done anything similar to what Dave at Thunderfunk did with the AMP 420, but with their tube amp? AKA, has anybody bought, say, a lower priced tube head like a traynor YBA 200 and upgraded the capacitors, resistors, and/or inductors to tighter tolerance, higher quality parts? If so, has it made a positive impact on tone, clarity, noise, hum, headroom, etc? Post pictures of before and after if you've got em'!