This is a step-up transformer using a small transformer, AT403-2. Connection is via a 3.5mm stereo plug. If your analog source is quiet and you have to turn up the amplifier volume quite a bit, inserting this between the source and the amplifier will increase the volume of the source. This step-up transformer is for analog sources, requires no power, and is easy to connect. Theoretically, it can boost the signal by approximately 10 times. The impedance is configured as 1200Ω:8Ω, the same as the ST-32. Please refer to the internal product images and detailed transformer description images to determine compatibility, etc.