High End headphone amplifier recreates the sound with a sense of high speed, warm and relaxation that feels lingering in the air. Fully discrete design that can also be used as a preamplifier thanks to its low impedance and variable gain. S501 utilizes long life, high reliability reed switches with vacuum sealed ruthenium contacts that result in the smallest possible degradation of the sound quality.S501v (voltage-mode): Inputs: 3 x LineS501i (current-mode): Inputs: 1 x Line, 2 x Line for current-modeOutputs: 1 x Headphone, 1 x LineSize: W300xH