I'd never buy from a local sotre...ever. The warranty means nothing to me, as I have owned 100+ car audio things(be it subs/amps/speakers/HUs/etc.), and I have only had ONE thing fail on me, which was an Xtant amp that I ran at 1ohm for 3 years, even though it wasn't rated for it....so it was my fault anyways.
Warranties are good for people who have no idea what they're doing, have no audio knowledge, and have been prone to fvcking things up. But even when they do fvck it up, will the manufacturer's warranty cover it? Probably not if it was user error, which is the case 95% of the time.
At basically any online store, if the products comes to you defective, they'll replace it. Do those online stores carry warranties? Yes, some carry 1 year warranties and such. Will I ever need to use it? More than likely, not.