ME-1 volume level isses ???

We have an Allen & Heath GLD-112 with the ME-1 personal monitor system. I have had a few singers/players say that during the first 30 min or so of rehearsal the monitor levels seem good as they make slight adjustments then the level drops noticeably. I cannot account for this since we never adjust preamp or trim levels once rehearsal has begun. Has anyone else heard of a similar phenomenon?

I always try to deal in fact not “it seems like”, so I am not sure this is an actual level change or just perceived level change as their ears acclimate to the higher volumes.

When are they saying that the change occurs? Is at all at once for all of the band, or gradually over a longer time?

What signals are the ME-1s receiving? Straight from the input socket, or from a direct out picked from somewhere in the console?

Chris