A lot of people who use straps tile the dulcimer slightly upward so that the bottom doesn't sit flat on their lap, thus enabling the back to vibrate more freely.  That makes a noticeable difference in volume, and perhaps a slight difference in tone as well.

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Dusty T., Northern California
Site Moderator

As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie

I hadnt thought of that, thanks for the reply. 

No, as I don't use straps.  However, it may seem different because you aren't pressing down on the instrument so firmly, and thus allowing it to vibrate more.

I have a new to me Folkcraft, took it to a luthier and had strap buttons put on it. I swear it sounds different now. Has anyone experienced this? TiA.