Okay so I am having an on and off problem with my system. First let me tell you what I have in the car.

Alpine head unit cda 9855
Alpine 4 channel amp
6x9 alpine type r speakers
12" alpine type e sub

so heres the problem...I turn on my car and everything turns on for about 2 seconds then the rear speakers and the sub turn off (that's what's hooked up to the 4 channel amp). I checked the amp to see if the power turns off but it does not. So I was thinking that maybe there is something wrong with the amp(of course.)

All of the settings are within the speakers range so I don't think that that's the problem and the RCA's seem to be good cuz I'm getting sound for a couple of seconds each time I turn the car on. Power cables are ran down opposite side of RCA's and as I already said amp is getting power the entire time. So I'm pretty stumped at this point...I have a couple of older amps that work so I'm going to hook them up to see if it is the amp or not but until then I was just wondering if you guys had another suggestions as to why it is doing this.
...Thanks for the help in advance