I got the old MTX Thunder 280 out of the closet today. It powers the rear speakers now. The Alpine under the seat used to do the rear but now it waits for the Kenwood 6X8's going in the doors. There's only a low pass filter in the amp, so I got a pair of 70Hz hi pass Fmods. I think the amp is from 1998 or 99, so I hope it lasts for another year or so. So far it's doing well.
