Here's a nice pretty eTap that I've made...........
https://app.box.com/s/3ib8ei8y56jriyp3s1kafznvljx30yxa
https://app.box.com/s/ae8tf9wyrgwltdzoju4ts31fvkjhu3u8
2 valve pre-amp, pentodes.
Uses any 12 volt, 1 amp power supply, AC or DC, polarity irrelevant.
Concentric level potentiomers. Inner for input , outer for output.
Uses inverter for HT , not transformer.
Will burn well if wood shortage.