and noted none of them list output impedance.
It's a long shot but in the hope that someone might have insight...I'm shopping around for wireless IEM system to use with my Etymotic ER4. Basically it's a UHF audio transmitter and reciever with integrated headphone amp for stage use. So far I've looked at Sennheiser and Nady units and noted none of them list output impedance. Anyone have experiences or recommendations?