Something weird has happened to my truck's sound system and I need your help to figure it out. I have a Pioneer head unit with Kicker component speakers in the front and full range in the rear with a powered Kenwood subwoofer under the seat. It has sounded amazing for a long time but about 2 weeks ago while returning on a business trip I started getting bad distortion if I turned the volume up past 15. Normally I can rock out at 25 before I need earplugs and stop twisting the dial. Nothing was changed in the truck, no service (I do all my own work) and no one else has driven it. I thought maybe I burned out the head unit's internal amp so I just bought a new one and stuck it in this morning but it didn't help. it's not source dependent although USD (which is about all I use) does make it worse...probably because of not adjusting SLA so it's a little more power than FM. Because of my long commutes between cities for the next 2 months I won't be around a stereo shop that'll be open when I'm free so I'm hoping you guys can help steer me towards a solution.