I am building an amp using AnTek toroidal PT (two 6.3V 2A heater supplies). I decided to put a DC supply in for the input valve since 4xEF80 plus 3x12AX7 puts me just above 2A. I put in a simple bridge rectifier for one of the heater supplies with 4700uF smoothing cap. The AC supply with the light bulb limiter on is 6.7VAC and the DC supply is 8.5VDC (no tubes installed). For one 300mA tube draw, I would have to put a 7ohm dropping resistor but I don't think I want to mess with it. Would have to buy several more resistors to dial it in once everything is up and running. Thoughts from those that have implemented DC heaters and made them work? Guess I will go back to all AC heater supply for all tubes (with DC elevation of course). If I put everything on one heater supply then it would be about 2.1A assuming 300mV from all tubes. I am guessing I will have to parallel the two 2A heater supplies.