I had a JVC KD-R980BTS stereo which recently got replaced by a Kenwood eXcelon KDC-X303 to hopefully solve a problem I've been having which is that after about 20 minutes of loud listening it'll begin to distort real bad and eventually cut out entirely, so I thought the amp in the JVC was going out. Lo and behold, the Kenwood did the same thing! I was super upset and then I remembered something: I replaced all my door speakers with JBL GX602s about a year ago, which then come to think of it, is the time the JVC began acting up the way it had been. I looked up my JBL speakers and they're not actual 4 ohm speakers like the salesman told me. They're 2.3 ohms but marketed as having "true 4 ohm technology," supposedly, after you account for the resistance from the car's wiring harness, up at the headunit the speakers will be seen as 4 ohms. Spoiler alert, that's a load of bull! I pulled my stereo out of the dash and metered at the harness, the highest resistance I saw was 2.6 ohms. I pulled the JBLs out and dropped in a set of Fosgate Punch 3-ways and problem solved. They lasted over an hour at full tilt so they pass my test lol.