If you have an amp with high level inputs that means you can tap into the speaker wires to feed your amp. It is called high level because the signal has already been amplified as opposed to a low level signal which needs to be amplified before going to a speaker. If your amp only has low level inputs and you still want to feed it from the speakers wires you will need to add a line level adaptor. If your X5 has DSP chances are you have the same audio connector as mine. Check your stock amp and see if it has a 15pins connector. The stock amp is normaly located on the left side behind the flashing. To check the pins you will have to eject the connector from the stock amp. This is the large connector that has a dozen or so wires connected to it. If it has 15 pins then follow the instructions I posted in the previous post. http://www.xoutpost.com/stereo-system...nd-system.html
Good luck