Electronic Interferrance

["Dupree, Robert A." <rdupree@sidley.com>]

 Using what I thought was better judgement; I went to a local Car Stereo   
shop and had them install all new set or rear speakers (Kenwood component   
set) and wire in my amp.  I had replace the Audi head with a Sony XRC-210   
last year (adequate for now) and thought I would use the RCA outs to run   
the rears.  I asked them to install a spare Coustic 30wX2 amp that I had   
from another car.  They did a nice job on the install, but after it was   
done there was a severe whine from the amp directly related to the   
alternator / engine speed.
 One lister had previously mentioned that a good monster wire set of RCA   
cables solved his problem.  I am wondering if anyone else can point me in   
the direction to eliminate simpler (less costly) options.  The shop said   
that it was the fault of the amp  and that Coustics are known for crappy   
electronic noise protection.  Why couldn't he have said this BEFORE the   
install?  FYI: the whole power booster setup has been bypassed, as well   
as the headphone jacks on the rear deck.  Also I was able to lessen the   
effect by turning the gain down a bit, but I still hear it when   
accelerating during periods of non-blasting music.  ALL IDEAS ARE   
APPRECIATED

TIA
Robert Dupree
'87 5000CS Quattro