Your church buys its first in-ear system to replace the WL’s front/center wedge. The tech removes the wedge, and routes the WL’s monitor signal into the new IEM system. At sound check, the WL puts his earphones in and starts to sing and/or play. He promptly says “my mix is different!” The tech responds “nope, it’s the same mix you’ve always had”. Who’s right?
They both are. Remember that with the wedge, the WL heard the monitor signal AND his acoustic surroundings as a total package. Now that his ears are essentially plugged by earphones, he hears only the monitor signal provided, and DOES NOT hear his acoustic surroundings. He relies 100% on the monitor mix he receives. The tech is sending the same mix as before, in the wedge, but the monitoring experience now sounds totally and understandably different to the WL. For this reason, the transition can be startling and potentially frustrating for new IEM users.