Some factory radios and amplifiers will not work without sensing that its speakers (low-impedance loads) are connected to their outputs. So adding a sound processor that uses the factory wiring for its inputs, like a JL Audio FiX 82 or FiX 86, would normally result in no audio at all. JL Audio's FiX-LSA-4 load-sensing adapter plugs in line with your FiX processor's inputs, presenting a load to the factory system, so signal flow gets restored and the music plays on.
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JL Audio FiX-LSA-4 4-Channel Load-Sensing adaptor for use with FiX™ DSPs Provides low-impedance load