"PAC SNI-1 Ground Loop IsolatorGreat for eliminating ground loop noise from radio pre-amp outputs. Perfect for eliminating DC Current from your RCA cables. Excellent at reducing most noise in your RCA signal path.? Close to perfect response of +/- .03 dB from 20-20kHz.? Unlike other manufactures which use 1:1 transformers, PAC utilizes proprietary audio transformers for a 1.3 dB gain. "