I have a kenwood 8405 4 channel amp powering my 4 door speakers and the other day in the middle of a song they decided to shutoff. I turned on and off the radio and the amp resumed working a couple days later the same thing happened but the amp will not turn on now. All wires i checked and swapped out with my kenwood 7205 which is working and they work so i know it isnt the wiring. Also both fuses are good on the amp. I noticed that when i have a hot power and disconnect it from the amp while still on it will light up as if its working then power down because there is no power connected anymore. It would seem that the amp is fried or something else is wrong internally anyone else have this problem??
I have heard of people having lots of issues with kenwood amps overtime so I am not surprised, you should probably disconnect all the speakers and try one at a time just to make sure there is not a problem with one of them. I am certain that you don't own a multimeter so I won't ask you to test the speakers impedance or the input voltage at it's terminals, sometimes fuses are not blown but develop poor contact. Anyhow there is a real chance that it went out anyways.
so it was a blown speaker that forced the amp to go into protected mode then I ran into a problem with picking up interference from the car alternater which turned out to be from a blown microfuse inside my pioneer head unit which was resolved by grounding my rca cables to the head unit
I figured you'd have checked the speakers first. Sorry about that. Also be aware that if you have a blown speaker, chacnes are there's another problem that caused the speaker to blow. Speakers very rarely ever just "blow" from "too much power." The cause is usually clipping from the amplifier caused by too small of an alternator, too small power and ground wire gauge, a bad ground point, or the gain on the amp being turned up too high. Those are the most common causes of clipping, and subsequently, of blown speakers.
The Pioneer thing is very common. Happens all the time.