I have the same amp as you and straight from the manual it says this for Level, " The input level control allows you to match the amp input sensitivity to the output level of the Radio/CD player from 0.2 volts to 9 volts when using unbalanced RCA cables. The Level control needs to be adjusted to match the Line Level Sensitivity (this is the amount of voltage the radio/CD player RCA's provide). Example: If the radio/CD player Line Level Sensitivity is 4 volts, adjust the amp Level control to 4 volts"
