it seems to me that it would be logical to have both...//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif
some amps DON'T have internal/external fuses, so you'd need to fuse before the amp anyways (even if it's in the trunk), and you DEFINATELY need to fuse at the battery (protects the WIRE from burning your car down).
that's how i fried my tantrum, which is being repaired, should be done this week). didn't fuse at the amp (cuz my kx1200.1 had a fuse on it) and the first time i turned it on, i heard a whine that went from low to high, then a "pop" and that was the end of the amp.