I attended a reasonable performance of Five Last Years last evening and spent the time wondering why such an intimate show required body mikes and amplified instrumental ensemble. Is this show always performed like this?
How big is the theater? Where is the band located? Is the audience accustomed to listening to entertainment louder than necessary? (the answer is always yes)
Reasonable as in decent? Also no matter what show it is, if the space is big enough you're gonna need the actors to have body mics, we do that at my high school in our huge space. And the orchestrations of The Last Five Years are quite excellent, so maybe that's why they need to be loud? Your post is quite confusing...
Having just watched the Fun Home "Changing My Major" performance on Late Night, I couldn't help but giggle at this question. Perhaps it's similar to "Went to the meeting at the gay union tonight ... a lot of political talk, almost too much, but ultimately a reasonable amount."