Hi Ned,
A mixer's compressor/limiter circuitry can work well to clamp down on most extreme volume sources.
But, if there is noise after the mixer, for instance a cable out of the mixer that isn't in excellent condition and
has some noise on it, then the mixer can't catch that.
This is why it's preferable to have limiters on earbud bodypacks.
So if you use the mixer for limiting, make sure your cables/connections are in excellent condition.
And use a UPS, battery backup unit, to power the mixer, which is good practice anytime.
The Mackie Aux-Master compressors can be set to work as limiters:
Set the ratio to infinity:1
Use a short attack time, maybe 10ms.
Set a release time of about 200ms.
For Threshold, get the earbuds at a good level and adjust the threshold so limiting just starts to happen for very loud passages.
Tweak as needed.
Good health, Weogo