I posted this on Swedespeed as well, but here's my dilemma. I just bought a 2004 C70 with the SC901 and Dolby Pro Logic, and it appears to have the well-documented whine in Pro-Logic mode. I just talked to the Orlando dealer and they told me that the processor is part of the SC 901 (and that to replace the radio it's not a plug-n-play deal. They need to do some programming at the dealer, which I know is not true as the as the seller replaced the old radio (CD player wasn't working) in about 5 minutes.) With a little digging on eBay I found this: Dolby Processor 3533799. Is this the processor I'd need to replace to fix the whine? If it is, does anyone have the part number that I can call the dealer with to buy a new one (and would that fix the whine?) I'm assuming since this issue has been around since pre-2004, the new processor would have the fix installed to cure this whine. Also, is the processor located directly behind the HU? Thanks for any insight.