That Byrd is very nice! The individual voices came across very well on my IEMs.

I'm used to reverb as well, and the complete lack of reverb in these recordings still sound a little weird to me, as if they are singing in a closet. But even in the 15th and 16th century vocal polyphony was likely performed (often?) in places other than the resonant nave or choir of a large church. I read that aristocratic (or ecclesial) patrons would have singers perform in private chambers, and performance of votive masses at a private chapel to the side of main space in the church would have very different (and quite dry) acoustics.