my amp did the same exact thing over and over again... i had two problems.... for one the amp shorted at the manufacturer.... and two it kept blowing the fuse because the capacitor in there that shorted kept negatively charging... what kind of amp do you have? i had an audiobahn 8000T ....... it blew 6 subs that i had bought before we actually new there was a problem with the amp.... it kept turning on, blowing the sub, then going into protect mode.... oh and you said it tones down, right? ok if you have a good altenator it should keep your amp powered for a short amount of time, especially right when the car starts because thats the largest electrical charge your car recieves.... if your subs are too powerful for this, make sure you go and get a capacitor, which is a device that charges itself, so you dont pull too much electricity off of the altenator which powers the car after you start it.... a cap should run you from 50$ to 100$ depending on how big of one you need... hope this helps... or is the answer to any questions...