the car is a 2007 cadillac cts, and it has odd speaker placement from what im used too..it has 4 6.5'' in the door and 2 tweers in the front which is common, but it has 1 3.5'' speaker in the middle of the dash board and 1 3.5'' speaker in the back so would a 4 channel amp be fine or will the 2 speakers that are 3.5'' need there own amp? again my noobness is showing so i would appreciate the help..thank you