WIDELY APPLICABLE: Sound mixer with two volume control knobs, which blends multiple channels into a single channel and is compatible with various devices. Suitable for musical instruments, microphones, mobile phones, computers, power amplifiers, speakers, small stages, drum kits, pre-mixers, and other sound devices, with a DC 5-12V power supply and a 5.5 x 2.1 mm power input. AMPLIFYING TIME: The 6.5 mm port for dynamic microphones is amplified 75 times, the 3.5 mm port for condenser microphones is amplified 22 times, and the 3.5 mm stereo music input port is amplified 5 times. 3 PORTS: Once the microphone and music are amplified by the stereo sound preamp, they can be output independently or mixed together. There are three output ports in total, and the mixed output port can directly drive headphones for monitoring. ULTR LOW NOISE: The all-aluminum housing of the headphone mic amplifier completely isolates electrical interference, and the MC33202 rail-to-rail op-amp ensures the loudest sound at all output levels, with very low noise operation and excellent sound performance, making it ideal for desktop PA systems. Please use a high-quality, low-ripple power supply; poor quality power supplies will not work. INTERFACE SIZE: The 3.5mm interface of the biased preamp can be used with common electret and condenser microphones, and the 6.5mm interface is for dynamic microphones, which can amplify both wired and wireless microphones.