fingerstyle playing on a budget
Instruments- discuss specific features, luthiers, instrument problems & questions
Lisa Strumelia has a Noter & Drone Blog, and I wrote a booklet years ago called Get Noterized, both of which are accessible from here at FOTMD. Many of us who primarily play N&D do play by ear, but we also simply use just the melody line from other dulcimer tabs. There are other sources for hard-core N&D players as well. It all depends on the kind of music you're interested in.
BTW the more correct designation for your tuning is DdAdd. The D and the A are in the same octave, but the d's are an octave higher than D. The octave setup Dd for a 5 string dulcimer is intended to give an added richness to the sound compared to the older DD couplet.