[chris15]

Ok, first off, there's a common misconception involving the power handling (wattage) of speakers. Note that phrase: 'power handling'. The 300-watt rating that your speakers have does not mean that the speakers operate at 300-watts constantly. What that DOES mean (in general terms) is that your speakers can ACCEPT a maximum frequency of 300-watts FROM a source (your stereo). Your speakers don't affect your stereo, your stereo affects your speakers.. make sense? So when the Crutchfield tech told you that your stereo can 'handle' the speakers, he wasn't wrong-- he just didn't take the time to correct the misunderstanding.

Now, on to the speakers.. If you can access them easily, I would test them. Remove the speaker wire connectors from the speakers and use a 9-volt battery with two leads from positive to negative of the battery to the positive and negative of the speakers and see if you hear anything. (Don't worry, the battery won't harm your speakers whatsoever.) It should make a muffled sound when you move the wire leads around on the connectors, kinda like someone's rubbing your head with a pillow. If you do hear something, your speakers are fine. On the other hand, if you hear nothing, there's a very good chance your speakers are bad.

Secondly, I THINK you implied you're not using an aftermarket amp, but just in case-- are you using an amp? If you are, then there's another loop of troubleshooting for that situation.

Seeing as you have power to your headunit, I doubt it's a fuse. Sounds like it's either your speaker connections or the speakers themselves.