1/2 watt will do. Don’t go by the colors spec-ed in the book, use the wiring schematic you got with the transformer. If you didn’t get one, check with the manufacturer. Even the same transformer manufacturer changes the color of the leads sometime, so be sure you have the correct info for your specific PT (and OT too, for that matter). The popping “boost” switch in the amp project video is easy to fix, I think it’s addressed in another forum topic on the TAN site. Also, some of the hum may go away when he gets it in a cabinet with a shielded back. By the way, those Jensens would sound a lot better with Ted Weber’s break-in process applied. The 10″ jensen is really transformed with that treatment.