I dont think this is the problem because my front speakers in the kickers are FAR out performing the Inifitys in the back - and they are STOCK speakers.
The infinitys should be getting 50wrms a piece from the amp. And the definatly are NOT.

Everything to me seems to be leading to the amp...
Im going to get a multimeter in the next day or so and find out whats coming out of it.
Even if its a faulty deck preout or something should the amp still not be putting out 300wrms on the sub channel? Just shitty quality or something?

Thanks