I often record small to medium size a cappella choirs (usually live, using a simple stereo-pair of condensers), and normally the sound is quite satisfactory, but when I compare my work with my reference recordings of professionally recorded choirs the sound seems to lack a certain 'sparkle' and instead sounds dull and heavy. I often end up trying to fake it by bumping up the high end EQ a bit to make it sound less dull but that often ends up making the sound too tinny and bright.
Does anyone have any advice? Any good vocal exciter effects I could buy? Maybe even relatively inexpensive outboard boxes? Or is there simply an EQ or dynamics trick I'm missing?