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.
Do you fret with a noter or your fingers? Strum with a quill or a pick? Flatpicking? Fingerpicking? Fingernails or pads? At what angle does your pick/quill/finger strike the strings? Do you have a light touch or are you digging in? Do you play at a consistent volume or do you want a wide dynamic range?
Drones? Chords? Up the fretboard in the 2nd octave? Scale boxes across all the strings? Old time? Jazz?
If we took one dulcimer and passed it around, each of us would make that dulcimer sound different. Plus we all have different taste (and different ears). Sometimes at a festival I'll play two dulcimers and hear a whole world of difference between them, while my poor husband (who does not play dulcimer) does not discern any difference at all (and hence does not understand the objective fact that I need to buy just one more).
I am sure there are people who think a Carol sounds 4X better than a Gibson... maybe 100X better... and people who think the Gibson sounds better. Depending on how you play and what you're listening for, there might not be any significant difference between them.
The often-inconvenient truth is that nobody else can tell you what a dulcimer sounds like. You have to play it and hear it for yourself.
