Jerry Galipeau of World Library Publications offers the view that Catholic Church choirs should unplug the microphones and sing with an acoustic sound rather than an amplified sound.
This is outstanding advice. I quite often find myself in parishes that have spent huge amounts of money on musical sound systems that end up sounding more like concert halls than liturgical spaces. When conducting one workshop in such a space, I unplugged all the gizmos myself, much to the outrage of the parish's "sound technician."
"That guy might know about music but he knows nothing about acoustics!" he was reported to have said of my actions.
The trouble here often stems from a technician whose tools and approaches are designed for recording studios and concert halls where the only goal is to record or project a particular sound set onto a listening audience. The liturgical choir, however, is there to assist the ritual and be part of a sound framework that is broad and inclusive of the entire space -- to be part of something larger than the sound it is making.
What Galipeau doesn't mention is that there are serious issues of musical style to consider here. Chant in microphones within a dead space can sound...not quite right. These contraptions are made for popular styles of music with strict meters and hard edges like srumming and drumming. Chant and polyphony call for a live space with a natural acoustic, and in such a space a piece of rock music can sound...not quite right.
So I'm not sure that it is really possible to talk about acoustics without dealing with the style issue. How a parish deals with the issue of amplification can be very revealing as to what the designers and decision makers regard as the modal music of parish life.