Tired of straining to hear the headphones? The HP4's four 130 mW headphone outputs are clear, clean, and screaming loud, all packed in a compact, 1/3U chassis. Features include balanced L/R line inputs and outputs, global mute, overall level control, and sum to mono. The line outputs can feed another HP4 or an HP60. Features include: · 4 screaming-loud (130 mW per channel) stereo headphone amps · Mono summing · Monitor level control and mute · Daisy-chain multiple units via monitor outputs · Compact 1/3U rack-mount chassis