Description: The N-684V is a four-channel adapter designed to interface aftermarket decks to factory amps (i.e. Sony speaker level decks to Ford Explorer OEM amps). There is no loss of signal level through the full bandwidth circuitry. The signal level can be adjusted from a maximum of 9.5 volts rms down to zero volts. This is a great feature for optimizing the S/N of system and a must for competition or demo systems. Turning the knob clockwise increases the signal level. At the amplifier/speaker we recommend a 1:3 gain structure for most systems. The N-684V is fully transformer isolated with phase and frequency compensation to prevent noise and damage to aftermarket or OEM components. The N-684V is safe and easy to install. The N-684V features four floating speaker level inputs and four floating speaker level outputs.