The F388-D is a powerful and durable headphone amplifier in 19 "format with balanced stereo inputs on the back. The item features two stereo amplifiers, each equipped with volume and balance control. The gain can be adjusted internally to achieve -12 / -6 / 0 / +6 / +12 dBr. The amplifiers are very low-impedance in the output in order to be able to drive low-impedance headphones without any coloration. Due to the unusual high internal operating voltage also with high-impedance headphones a more than adequate sound level is maintained.