alternate power supply

i'm trying to figure out the best way to install an alternate power supply to my cd receiver. The unit has some issues that i have diagnosed as being ENTIRELY non vehicle related but as expensive as it would be to fix it i'm thinking of just side stepping the issue... what happens is that when the ignition power source is inactive (stereo SHOULD be in sleep mode) the unit flips out and switches on/off sporadically and loses all the presets. I bipassed the ignition and whent direct to the batter which solves the problem when the car is off, but when i start the vehicle there is a brief power loss that has the same effect as above and i lose all the settings and the stero turns on as if for the first time... what i want to do is put another power source in parallel with the main 12v and have it on some kind of switch so that during that brief instant when main power is lost the secondary will support the functions of the deck. Could this be done with a simple not switch on a parallel 12v (2 series 6v) with a small capacitor to prevent surge etc? Or are there capacitors that could provide ~1second of power during main loss? thanks rif you can't feel the beat, the rest is just noise!

 is this an aftermarket stereo? if so  you should have 2 power wires 1) to your memory (constant 12volts) and 2) to switched 12 volt.  it sounds as though your 12 volt constant isn't providing 12 volts consistenly.  If your radio doesn't work properly with the power may I suggest that you could put in a switch with a relay and control it's igntion power on/off with the switch. Then make sure that your 12 volt constant is constant, move it if you have to to out side of the power harness but still constant.Joshua Hickey