Help please!

Today I installed a CDA 9807 bypassing the infinity amp by wiring the speakers directly to the HU via the amp connector. I get fine sound in back, but the sound in the doors is BARELY audible. I did not hook up the dash speakers (intentionally, at least). Even with the fader all the way up front, you can barely hear them (the doors), and the whole system sounds WORSE than the factory x( .

Could I Have accidentally switched + and - at the HU? I checked the connections at the amp connector, it's correct, but if I did that would it make a difference in sound, or would it even play at all? Barring that, should I undo the wiring and get that harness that uses the factory amp for like 25 bucks? I'm sorry, but I feel like the biggest schmuck in the world right now because I just dropped $$ on a HU that sounds WORSE! please help!

thanks so much

Vandy