When you have no more bodily holes to shove IEMs into.
When you forget that you actually have a pair of those whatevers somewhere or other. It happens more easily with IEMs because they're little than it does with headphones.
See Clemmaster's post just above ;)
When you start to pair IEM to musical genes and locations (bedroom rig, office rig, etc.)
Alternately, when you start asking other online forums which IEM tips to fit your pet’s ears.
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