I don't like the idea of "adaptation studies" as the rubric for my work. It seems too linear: here is a work of literature, and we can see it adapted into various other media, like film... I guess that's inevitable in the way I've set things up, but I'm not overly enthused about it.
Traditions of "interartistic" comparisons or "sister arts" provide another path. Googling this, it is obvious that the majority of work has to do with literature and the visual arts. Comparisons with music and literature are a separate thing, and not very connected with the usual discussions of ekphrasis.
Ekphrasis is mostly about modes of representation or mimesis. The painting is a literary object, telling a story that can be reproduced in a poem, for example. Or a literary painting can be the representation of a pre-existing literary narrative. The comparisons come easily, right? because you have the same subject represented two different ways.
Writing on song we have the same ready-made comparison: we have the text itself, and the text as lyrics to a song.
What is missing is the idea that the human imagination itself is interartistic. We don't have to posit the various media as very different from one another, and then bring them back again for comparison. There have to be more interesting ways of doing this.