STAX SRM-400S Electrostatic Headphone Amplifier with SR-X1 Headphones For that reason, when STAX sent us their new SR-X1 ear speaker for review, they also sent along the SRM-400S Driver Unit as well ...

This is clearly not something that one can drive with a Dongle DAC or smartphone – or even standard headphone amplifier. Those who wish to tumble down the electrostatic rabbit hole require something ...