Jl xd600/6 and technic harness is the standard Hi Fi Fix.
http://www.e90post.com/forums/showthread.php?t=792322
This guy is on the right path for a base system it won't be to different for Hi Fi. the link above
Also
http://www.e90post.com/forums/showth...=759664&page=2
Reason's for the XD
Its a quality mid range priced amp.
It has the exact number of channels to match Hi Fi(xd 600/6)
It fits in the same area as the OEM Hi Fi amp
It has the right kind of Inputs to be compatible with the
Hi Fi Head Unit . (balanced differential inputs)
If you get good speakers with just the amp its pretty awesome.
If you like old style stereo with Morels and Jehnerts this is
an audiophile level system.