The HMA-41 4-Channel Stereo Headphone Amplifier from Polsen features a durable, compact, and easy to use design for a variety of professional and project applications, including studio recording, band rehearsals, and more. It features a high-output level that allows for precise monitoring at high volume, while its low-noise circuitry ensures clear reproduction of your sound. Each of its four channels boasts independent volume control and amp circuitry, which allows for a wide frequency response of 20 Hz to 20 kHz for full-range stereo sound while assuring no signal loss when all 4 headphone outputs are used simultaneously. The unit features a 1/4" stereo TRS input, and four 1/4" TRS headphone outputs. To assure compatibility with a variety of headphones, Polsen includes four 1/8" to 1/4" adapters as well as a stereo mini cable that, when used with one of the included adapters, allows you to connect a device with a 1/8" output. Durable, compact, and easy to use High output level for precise monitoring at high volume Low noise circuitry Four headphone jacks each with independent volume control Wide frequency response (20 Hz to 20 kHz) for full-range stereo sound No loss of signal when all four headphones are connected Includes 5 ft (1.5 m) stereo mini cable for connecting devices with 1/8" output (use included 1/4" adapter) SPECIFICATIONS Channels: 4 Frequency Response: 20 Hz to 20 kHz Input Connections: 1x 1/4" (6.3 mm) TRS master input Output Connectors: 4x 1/4" (6.3 mm) TRS headphone outputs Maximum Input Level: +14 dBV Maximum Output Level: 20 dB per channel Input Impedance: 100 k?, unbalanced Output Impedance: 51 ?, per output Signal to Noise Ratio: >90 dB THD: <0.008% Power: 12 V DC, 150 mA Dimensions (L x W x D): 3.9 x 3.2 x 1.2" (100 x 80 x 30 mm) Weight: 9.6 oz (272 g)