http://www.decware.com/newsite/mainmenu.htm

(Go to "Tube Gear")

This one really caught my attention. The ZEN amp SE-84. Personally I'd buy the kit and save $100. I tinker with electronics from time to time so constructing it would not be a problem.

For tubes that I replaced in my bass amp, I went here http://www.eurotubes.com/ and I found they added some nice warmth to the sound. They have some nice amps as well.