The PAC Audio SNI-1 Ground Loop Signal Isolator is a high-quality audio accessory designed to eliminate ground loop noise between the audio source and radio in vehicles. This isolator is compatible with portable devices that have RCA audio outputs, including preamp outputs. With a frequency response of +/- .03 dB from 2 Hz to 20 kHz and utilizing proprietary audio transformers for a 1.3 dB gain, this unit ensures clear and crisp audio quality without any interference.