There's a huge factor in the sound of a dulcimer that often gets overlooked: the PLAYER! I'm not talking about skill level here (although we all know somebody who can take a $50 toy guitar and make it sound better than most people playing a Martin). I'm talking about the wonderful variety of playing styles that make each of us unique.
I completely agree. I would add that an instrument can sound very different when passed around to players even with similar styles as their attack can vary significantly.