What woods are you using for your dulcimers? Mahogany, cherry, black walnut, cedar, redwood, spruce,maple are sometimes used for dulcimers.
I keep some small blocks of wood in my house but large pieces and boards are in my aircondioned shop..I keep the AC on 75 degrees and I run a dehumidifier a few hours before I spray finish a bow. I have a cheap pinless and a pin type moisture meter. My risers blocks have a MC of 8-10% when I use them. I also check them after cutting them to rough shape since the pins only read the outside of the block.