The PAC-AUDIO SNI-1 eliminates ground loop noise between the audio source and radio. Some people call it a noise filter. Use it with portable devices that have RCA audio plugs.

If you've got your mp3 player, or some other audio device, connected to your car stereo and hear constant (or increasing/decreasing) buzzing or humming, you can use this device to eliminate most of the interference. You will plug it inline between the audio source and the radio. It has a female RCA jacks on the input side and a male RCA jacks on the output side.

It has close to a perfect response of +/- .03 db from 2 to 20,000Hz. It utilizes proprietary audio transformers for a 1.3 dB.