Amplifier fuse

Just make sure the power fire is fused no more than 18 inches from the battery.  If you've got that done, I don't see any reason why you would need an additional inline fuse close to the amp.  If the inline fuse near the amp is the only inline fuse, that is not good.  You've got to at least fuse the power wire close to the battery.  Other than that, I don't know if fusing it again near the amp is helpful.  I would probably guess not, because if you blow the fuse close to the battery, there is not going to be anymore juice running through the wire to even reach the inline fuse near the amp.  This is my belief until somebody tells me I'm wrong, which I always welcome. 

Some amplifiers do not have fuses built into them (Rockford Phosphate, older Orions, really old Alpines.......) These amplifiers should still be fused directly at the amplifier, especially when multiple amplifiers are used. Generally speaking the fuse at the battery is to protect the vehicle should a short occur between it and the amplifiers. If your amp does not have a fuse in it I would play it safe, put that fuse by the amp and spend the extra little $ on a second fuse at the battery, penny wise, pound foolish.