I set a Seymour Duncan up years ago under the strings in a flat space at strum hollow, so I could learn & use the Boss GT-1 during Harvey, the TX Hurricane. It is the only dulcimer I had with a flat space, all others had the strum hollow.
So, why not a removable Magnetic Pickup, floating above the strings?
One that would work, say on blocks (it's what I had around the house), having the 2 different sizes on a block (sides & tops) for different height fretboards - trying to be as close as you can without hitting the strings.
More bass away from end in strum hollow & more treble sounding closest to end.
Sounds best anywhere in the strum hollow or even up the fretboard some - notice this Dulcimer (the one everyone recently helped me set up) has cut out groves but not a true hollow area - need to have good string Vibration but still works well with this dulcimer and can slide it up or back as I like.
Overall, it does what I hope it would, read the vibrating strings from above & is interchangeable with any of my other dulcimers. The Humbucking pickup (only one they had at the Guitar Center) is taller then the wooden Seymour Duncan but with it able to slide up or back on the fretboard you can choose to strum in front of, or behind.
Like my other pickup - under the strings - this one floating over the strings, works beautifully & such a good idea - a passive Humbucking as a removable pickup, or any magnetic pickup to read the strings - Why hasn't someone come up with a design for an - Interchangeable Magnetic Pickup? I know Jerry Rockwell has a pickup mounted above his strings - not sure if it's permanent or removable but he has demonstrated how well it works above the strings, in his playing.
I think there would be a market for anyone's dulcimer not already having a built in pickup. Is this anything anyone has thought of or already designed or would like to?