DIY Line Level Converter for cheapie amps so you can use a powered sub - Techtalk Speaker Building, Audio, Video Discussion Forum
ACI speaker to line level converter for use with Force/Titan subs. These is the internal
Speaker-level inputs or line output converter (LOC)?
BOSS B65N Speaker Level to Line Level Output Converter
How To INSTALL a Line Output Converter w/ Stock Radio & Speakers 4 Aftermarket SUB AMP Installation - YouTube
Car Stereo Pit Fall #1 - Never Use Speaker Level Input on Amplifier
Xantech SLLC1 Speaker-Level to Line-Level Converter for MRC44CTL, MRAUDIO4X4CTL
Axxess Integrate Output Line Converter
Amazon.com: Scosche LOC2SL Line Output Converter Adjustable Amplifier Add On Module for Car Stereo, 2-Channel Signal Sensing Speaker Wire to RCA Adapter with Remote Control Knob, Black : Electronics
LoC-22 Fully Active, Two-Channel Speaker Level to Line Output Converter with Auto Turn-On
Subwoofer circuit: Going from speaker level to line level | diyAudio
TX-70A ‐ 25 V, 70 V, 100 V Speaker Level Input Interface - Unbalanced line output
Amazon.com: NuIth Car Radio Stereo High to Low Converter Wire Adapter 2-Channel Adjustable Amplifier Subwoofer Interface w/Remote Turn On RCA Car Line Output Wire Cable : Electronics