Amazon.com: KICKER KEYLOC DSP Smart Powered Line-Out Converter 47KEYLOC Bundle with Rockville ROCK ANYWHERE WaterProof Portable Bluetooth SpeakerwithTWS Stereo Linking : Electronics
What are line output converters?
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ALOC2 Recoil 2-Channel Speaker Cable to RCA Adjustable Line Output Converter with Remote - Recoil Audio
XLOC22X 2 inputs / 2 outputs High Voltage Active Line Output Converter — NVX