Noise in a factory amp

Hello everybody,

Here is my problem , maybe somebody can help me. I have a Lexus ES300 and I changed the factory radio to the new HU Alpine CDA 9856 and put the new Infinity speakers into the doors. To connect the HU and speakers I used the foactory wires and amp. When I made these  changes I start hear a humming noise in a amp. After that I connected the factory radio back and everything sounds good, I don't hear any noise.Also when I start the car I can hear a "pop" noise in the speakers right after I start the car. Any suggestions what can be wrong?

Thanks

You may need to locate and bypass the factory amp. Check the trunk. I hope your Infinity speakers are 4 ohm.My ex once told me I have a perfect face for radio.

To connect the new speakers and new HU I used a factory wires and amp. To me it looks the factory amp is not enough powerful to handle that load, so why I’m getting the noise. That humming noise drives me nuts when I’m listening the music, so I decided to put new wires and install a new aftermarket amp which I have.