Review on PAC LC-1 Remote Amplifier Level Controller,Black,Small: Advanced Audio Control at Your Fingertips by Norman Costello

I had a fun project with a dual 2 ohm subwoofer where I wanted to connect each voice coil to an independent amplifier. I knew I needed a bass knob and didn't like the layout options for using a knob or certain amp knobs (which use 3.5mm). This acts like a man in the middle controlling the level of the signals in the RCA cables. Pretty basic actually, just looks like a potentiometer in a box with RCA input and output jacks (all female) but that's not a disadvantage, that's what makes it great. Response time is instant which is great as this particular car has plenty of bass and you can respect red lights and turn off the bass without losing the music from your other speakers. It's also really fun to set it low, maybe 1/4, and demonstrate your system to a friend, and then, on the second drop, have it open wide and see a surprise if they weren't expecting it. Assuming you already have your standard RCA jack-to-jack connection from the head unit to the amp, you only need to pick up a short 3ft or 4ft section and you can place the LC-1 right in the middle.