any one know the power specs on 94 OEM premium amp?

[offroadford4x4]

I tossed one of my Kenwood head units in my 94 last night only to discover the headunit worked, but nothing came out of the speakers. Connected the "amp turn on" wire on the HU to the blue wire on the trucks harness and I had sound. So that means the truck has a factory amp. And it's sounds so much better than before and much louder. Turns out the truck has the factory "Premium Sound" but I searched google and here but cant find any specs on the amp. Does anyone here know what the actual (or at least rated) wattage output of this amp?

 

[rhauf]

The amp doesn't have an inverter, so its voltage is limited to the 13v the cars electrical system gives it, so output power would be the same as almost all after market head units; about 18 to 20 watts RMS into 4 ohms.

 

[offroadford4x4]

Then why is it so loud now? cause my kenwood puts out 15w per channel into the amp, then it amplifies that more? Kind of like adding a line driver to an aftermarket amp?

I've ran 35w per channel amps before to my highs and was never as loud as this. and these just are the OEM speakers from my F150 since the sploder ones were all rotten.