I have a musician friend who wants to take the ouput from his
microphone (XLR) and feed it into a Layla 20 sound card with the least
amount of added electronics possible as he's trying to avoid coloring
the sound.

The microphone is XLR and requires phantom power.

The Layla 20 has 1/4 inch balanced (or unbalanced, if desired) inputs.

Is there some sort of "box" that will do what he wants?

....
Krick