Installing an aftermarket amplifier in a 2010 x5 40d

[mr angry]

I have had enough of listening to the crap basic stereo and want to upgrade it. I have had a search online and can find very little on the E70. I have replaced the front under seat speakers with direct fit Focal units and now looking to do the same with the front door woofers adding tweeters.

I have bought a set of Focal 100 KRS speakers with cross overs and tweeters. Rather than just plug and play I am looking at adding an amplifier but unsure as where is the best place to locate it and where to find the speaker outputs for wiring to the amp.

Anyone done this or even any ideas?

[mr angry]

This isn't easy....I thought I would install the front door speaker, tweeters and crossovers just now leaving the amp until some time later when i can find the best way to do it. Upon removing the oe speaker it is not obvious what the polarity is on the two speaker wires. One is yellow and the other blue with yellow. I need to chop the original plug and rewire from the crossover but cant determine which of the two wires is positive. Searching online shows up mostly american wiring diagrams which have very different colours.

Help!