I have a late-2013 15" MacBook Pro running Mojave. It has the "combo" headphone jack that incorporates a mic input when an earbud/mic with TRRS plug is plugged in. I haven't been able to find out if the mics these earbuds use are electret condensers that require a biasing voltage and if the Mac is indeed supplying this voltage. There are adapter/splitters that take the Mac's TRRS jack and break it out into a separate mic and headphone jacks. I'd like to use a headset mic that requires 1.5 to 10 volts of voltage to work – I'm just not 100% confident pulling the trigger on this mic & adapter/splitter without knowing the true scoop. TIA for any help!