Hi, I have read some of the reviews regarding the quality of the P5 subwoofer....yup, looks marginal, but I think I am going to get one for space issues. I was wondering if anyone knows 1) About the installation?....easy?....complex? 2) If the unit only works with the OEM head unit or will it work with any head unit (I have an Alpine 9856)? Any input would be fantastic......Thanks in advance!