• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

DC heater (+/-) -> elevated?

I suspect the point of experimenting will be to find the best solution after having tried all posibilities;)
I have tried both regulated DC and AC heaters and even on high gain circuits (high gain guitar preamps) having the AC heaters biased somewhere between +20 and +90 volts have been jsut as good as reg'ed DC.
With the Aikido one tube (including its cathode) sits at high voltage, so I would place the heaters close to this voltage, preferably above.
Please post ur findings after your experiment.