Recently a few customers and me myself tried a lot of different power supplies in conjunction with the Kilimanjaro-Series Field-Coil Speaker(s).
Switching power supplies are not suitable for my field-coil speaker drivers.
I urgently recommend the use of regulated solid state power supplies with hum & noise below a few milli volts (typical ≤ 5mV).
Also very good results can be achieved by using a high quality mains transformer, a bridged rectifier (or ultra fast recovery diodes), a choke and a good capacitor. You'll be pleased.