HIGH END SPEAKER LEVEL INPUT TO RCA LEVEL OUTPUT. BUILT-IN GROUND LOOP ISOLATOR. ADJUSTABLE GAIN POTS ON EACH OF 2 CHANNELS THAT ARE WIRED IN FRONT OF THE ISOLATION TRANSFORMER. THIS ELIMINATES OVERLOADING WITH HIGH POWER INPUTS. RCA JACKS ON INPUT AND OUTPUTS BUT WITH RCA TO WIRE STUBS FOR SPEAKER LEVEL INPUT WIRING. THIS IS A PASSIVE DEVICE THAT ADDS NO NOISE. IF YOU DO NOT WANT THE ISOLATION VERSION SEE "ATTENUATORS".