Subwoofer LEDS - RGB, brightness controlled by amp
I am definitely not very knowledgable when it comes to electronics, but I did something similar to this once. I had my subwoofers hooked up to a 1600 watt amp, and used a separate 400 watt amp for the LED's. I wasn't sure if it was bad for the amp or the LED's, but it seemed to work fine. All I needed was audio splitters for the two amps and I used a small power supply from the cigarette lighter to power the amp and the LED's. (Of course I have my larger amp hooked directly into the battery). Here's a video of how it looked. I didn't have the LED's in any special place, I was just messing around. 

Here's the video