Tunes in the key of A major
General mountain dulcimer or music discussions
So the easy answer here is indeed to capo at the fourth fret and play everything you know for the key of D. You'll be playing in A. Folks do that sometimes to match the keys of standard tunes at old timey or bluegrass jams. Kitchen Girl, for example, is usually played in A, as is Salt Creek. Sally Goodin', Sourwood Mountain, and more.
What I don't get is the motivation here. Are there songs you want to play in A or do you just feel like playing in A for the fun of it?
Gary Gallier has arranged a few tunes in A out of a standard DAd tuning. But those are some pretty fancy tunes with very careful picking. Since the D note is found in both the D and G chord, that low string sounds OK when you play in D and G, but it will be out-of-place in A, so you have to be really careful and only hit that bass string when you are playing a D chord. When you are playing an A or E chord you cannot hit that open bass string at all.
See Gary's arrangements of Kitchen Girl and Road to Lisdoonvarna from the tablature page of his website .
Personally, when I want to play in A I use a baritone dulcimer tuned AEa. Simple, huh?

is pure Strumelia, for sure!
but also the dancing guy silhouette
.
Let's pretend that's a hamster chew toy smiley.
. It almost makes me tear up.
today and I just finished
so I thought I might ask if you guys
certain smileys or if they just make you want to
.
! Perhaps, when you heal a bit, you can try some fingerpicking. No picks needed.