Correction: the line-out converter by Peripheral is $19.95, not $39.95. I was thinking of the piece we have hanging next to it.

And Eclipse804's suggestion would also work(and save you some money) if your amp has high-level inputs on it.

There are 3 screws holding each back panel on. I start by removing the seat cushion. To do that, pull out on the little black rings that barely stick out from underneath the cushion, and lift up on the cushion while pulling. Once the cushion is out, you can see and remove the two lower screws easily. The other one you can get to by folding down the rear seat.

-Matt