Another: "garbage in garbage out." If your amp produces distortion so will your speakers. If the amp produces enough distortion it ends up costing you a new set of speakers.

Agreed.

Rather than saying the speakers are always the first, best upgrade, perhaps it would be better to say, "find the weakest link in the chain, upgrade that."

Agreed. It's just that in most of the factory systems I've seen, that weak link is the speakers and amplification as a set, with the speakers being the thing that's most in need of replacement.

Okay, in most factory systems there isn't even an amp at all, so you do have to upgrade that part anyway I guess.

And yes, a good amp is important. I'm just saying that as long as the amp is adequate, you're going to hear the most improvement with better speakers.