Check the listing for details. Option HLM High-Low Adapter Set for Plug & Play Subwoofer Quadlock Connection. Condition: New. Listed at 261.14 USD. Its “Double Activation Circuit” also generates a +12 V remote signal in two different ways to switch on connected amplifiers. It either detects the DC voltage potential on the speaker outputs of standard factory car radios or uses integrated signal detection with variable input sensitivity, which can also be activated. The standard equipment also includes “Power Save Mode”, which switches off the remote output if it lasts longer than 2 minutes. there is no input signal. Many vehicles with “CAN” or similar bus systems leave the car radio “invisible” for up to 45 minutes. activated, even if you have left the vehicle in the meantime. The HLM generates a high-quality preamplifier signal from the speaker signal of the car radio or amplifier of an original sound system, thus enabling the easy.