Went to best buy in search of some aftermarket speakers, and I found some that I liked. I wanted Best Buy's geek squad to do the installation for me because I didn't want to go through the trouble however the sales rep told me they would NOT be able to do the installation if my 2004 325ci has an amplifier. I went snooping throughout the trunk and I found this metal box connected via a bracket that was behind some of the trunk liner located directly behind my backseat. Is this the amplifier? If so how difficult would it be to replace my own speakers. I just want to replace the two speakers in my backseat because they are blown.