I bought my current 1997 F250 truck about a month and a half ago and it came with an already new sound system in it. It has a Kenwood headunit, kenwood amp powering all the door speakers, and a mini powered sub behind the seat. The other day I was driving it and heard a faint pop and now my sound on higher volumes isn't as crisp and clear as it was. It is like this on phone connectivity and also for normal stations. Sub and speakers all still work- just not as crisp sounding. This used to be an amazing system, but my stock Grand Marquis daily driver sounds better now. Any ideas what could've happened?