AKG HP4E 4-Channel Headphone AmplifierThe HP4E 4 Channel Headphone Amplifier from AKG features two stereo input and four stereo output channels of high quality audio. It can be used to add up to four headphones in applications for mixing, recording, and is designed with convenient switches on the front panel to enable you to select your desired input. Headphones require no adapters. The front panel is built with both a 1 8" and a 1 4" headphone output and volume control for each channel.