I recently replaced the stock headunit on my Mercedes SLK with the
Alpine 9833 and attached the ipod adpater.
The system works great, expect there is a whine that is constantly
audible. It does not matter if the engine is on or not, so it is not
"engine noise" per se, but is quite loud.

When I installed the HU, I used a wire harness, and used the stock
radio ground (Meaning I did not directly ground the Alpine unit, just
hooked it up to the harness, and thus the factor ground wire).

Is this likely to be the problem? Or something else?

Any help would be great.

BTW, the stock system is an amplified bose system with 6 speakers. The
amp takes input from the speaker wires, not RCAs.

Thanks
PT