This may be a dumb question, but nobody ever talks about them. Do you have to have a Zapco amp to use the Symbilinks? If you do I am interested in getting a Zapco, because I am trying to change my strictly spl piece of mind and get into sp more. I have a very very slight problem with engine and alternator noise that isn't audible to most people, but I can tell. And I was thinking that the Symbilink would probably take care of the problem. I really wouldn't have that much of a problem spending the money for Zapco, i've heard their still cheaper than JL stuff.
They are not cheaper than JL. Maybe some of old Zapco amps on eBay. If you're getting alternator/engine noise, it's probably cause of ground loop. Make sure your ground wire is less than 2 feet. Zapco/Xtant/JL/Arc Audio and few others come with a circuitary that help minimizing ground loop noise pickup. If you have the money then go for Zapco C2K 6.0 series. It's one of the best model from them. It may cost a bit more than most brands, but if you're into sound quality, then it's the best investment you'll make.
Yep. Great amps. Symbilink virtually eliminates any picked up noise, but that ONLY applies to inducted noise that you'd get from the RCA lines. It sounds more like you have a ground like Isaac said. Ground loops don't just come from the amps, check the head unit ground as well. Do a chassis ground if possible for best results. You can't use Symbilink with other amps, although I'm sure that Arc Audio will come out with something similar in the future (same founder/engineer as Zapco, Robert Zeff). They may already have something like that out, haven't checked in a while.
Ok. I know I don't have a ground loop from my amp, but it could be from the headunit, I didn't ground it in the best spot that I could have. I do think it could be from my rca cables though. I have some crappy rca's running from my headunit to my amp. I bought some better ones, rockford I think, but I haven't gotten around to running the new ones. I think this summer when I upgrade again I might look into getting a Zapco and using symbilinks.