No you won't and I don't see where it says that.
In a Hi Fi setup the amp only gets simple analog connections
The bluetooth and aux come from a separate module in most
cars before 2010 and at some point directly from the radio .
The only difference is that amp it gets all the same signals and
doesn't disturb anything else. Also that guy routing on the power
wire has the problem that the carpet won't go flush and is a bad
place to have it in case of a rearender.
I have done this and nothing happened to my bluetooth or aux.
Lots of people have done this here and there has not been one
instance of loss of bluetooth or aux due to a Hi Fi amp change.
The modules that do the bluetooth and aux are located in a different
position and communicate over a fiberoptic interface that you are
not messing with when changing the amp.
If someone told you this they don't know your car or what they
are talking about.
BMW stereo types
http://www.e90post.com/forums/showthread.php?t=352586
http://www.e90post.com/forums/attach...2&d=1266451970
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=343673
http://www.e90post.com/forums/showthread.php?t=138949
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/showthread.php?t=641323
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://www.e90post.com/forums/attach...1&d=1209780865
http://technicpnp.com/menuDiagrams/d...e90_92_93.html
electical e90 pdf
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.musicarnw.com/page-2/
http://www.bimmerfest.com/forums/sho...d.php?t=903551
http://www.e90post.com/forums/attach...4&d=1278871872
If you go to an aftermarket head unit you will loose the bmw bluetooth
and satellite and have a whole set of other problems.