Its not that complicated. I have only replaced one on my 7 series and I'm pretty sure its the same on the 6 series.. The amp was located in the trunk, left side, behind the cardboard fabric stuff (whatever you call it). Its approximately 12 inches long by 4.5 inches wide and deep. It was really easy. There are two connectors on the unit, one electrical and one FOC (fiber optic connector). The unit is held in place by 3 pullouts. The only tools you will need is to take the trunk cover off to get at the unit. It took me about 30 minutes and that's only because I had never done it before. Bet you I could do it in 15 or less now....
2006 BMW 650i Sport/Premium Package
+ Various Mods & Upgrades