Amongst many things the production crew for our musical Grimhilda! have been discussing are radio mics (but not USB mics) for the singers.
I find it quite difficult to remember to use this spelling; my tendency is to go for mikes, in line with the spelling of my own name. But like it or not the normal spelling by the techie people is 'mics.'
It's an oddity in spelling terms: I can't think of another word that ends quite like that and still sounds like mikes. When you look at it, especially the singular form, you tend to try and figure out how to enunciate the 'c'. Standing alone like that, with no 'k' or 't' to follow, it seems isolated. If there was another syllable or two before it, as in the word pandemic, we'd know that it was pronounced 'mick'. In fact, even looking at it bare, without other syllables, there's a tendency to think of it as a mick word, like endemic, systemic, polemic, academic, polemic.
But mic (say mike). Nah, it just don't ring true...