2-way amplifier/speaker selector: both working mode (2-IN-1-OUT / 1-IN-2-OUT), with A/B channel toggle switch, convenient to compare the sound quality of 2 pair of different speakers or 2PCS power amplifiers without plugging in and out cables repeatedly to avoid wearing the contact point of the sockets. Strong compatibility for audio device: support doing comparison between different types of amplifiers such as BTL, class A, class B, class D, tube amp etc.. Each channel can pass up to 200W power, also suitable for the comparison between most passive speakers. Purely mechanical passive circuit: no power supply is required, no loss of input and output signals during transmission, and no audio rendering or electromagnetic interference, providing HiFi lossless audio without distortion.