This Hum and Noise Eliminating Audio Coupler is a very handy 2 channel inline transformer coupler that enables the interconnection of audio modules without introducing hum and buzz, etc.

Applications:
Car sound: Enabling connection from receiver/player to power amplifier
Home theatre / Hi-Fi: Enabling hum-free connection between main and sub woofer amplifiers (use mono inline hookup in this mode. Ie. Left or right channel is required – not both)