+ 1 for the Tubes4hifi kit. I built my VTA ST-120 about 4 years ago, and still own it to this day and love it.....note this is the only tube amplifier I've owned. I now just have to install it back into my system, with my solid state gear. I built mine with the optional capacitor upgrade, and the stepped atenuator.
I have mine with Phillips 5R4GY rectifier that I like better than GZ37s or RCA NOS tubes. Power tubes are Tung Sol KT-120 power tubes, and roll various 6DJ8, 5963, 5814, 12AU7, 6922, etc - NOS Pre Amp/signal tubes.....believe I'm getting somewhere near 70+ WPC with the KT-120s.
Kit has great instructions and wiring diagrams (color coded), and was incredibly easy to follow. Fun project with a great amp, that is a tube rollers delight.