I was wondering if Remo djembe heads actually require changing if they're not physically damaged (punctures, tears, etc.) Since they're synthetic and impervious to a lot of the things that affect real skin heads, do they actually wear out? I've got a 14-inch Arthur Hull ashiko with a Mondo head that's scuffed at the edges and has what looks like a few grease stains in the center. I bought the drum used, and although it sounds good, I was wondering if a new head would make a noticeable improvement in the sound in terms of volume, sustain and dynamics. Has anyone else on this forum ever changed the head on their Remo ashiko or djembe and noticed a significant improvement sound-wise? Thanks.