MrSpeakers VOCE Electrostatic Headphones/HeadAmp Blue Hawaii Special Edition Electrostatic Headphone Amplifier – Personal (Audio) Best - Headphone Guru
Blue Hawaii Special Edition Electrostatic Headphone Amplifier - Suncoast Audio
Electrostatic headphone amplifier MusicTravel MT-F1b can match STAX electrostatic headphones. Frequency response: 5Hz-110kHz - AliExpress
HeadAmp - Blue Hawaii Special Edition Electrostatic Headphone Amplifie - The Source AV