Can I using Sennheiser HD 280 PRO on Mac Mini?

I've got that mini and those cans. They sound great hooked direct. They sound great running through a Mackie mixer. I suspect that mixer may have small amp. I bought them because of all the rave reviews from different audio forums. You have my two thumbs up. Very nice set of headphones without need for an external amp. Just cranked all volume to max and it will bring a smile and that "oooooh yeeeeah" uncomfortably loud but not quite to that painful threshold. Tweak with your EQ and get the SRSWOW plugin and they will floor you.

I say get them, you'll love them. One thing though, you'll have to do a daily check for "headphone hair" before work:-)

The headphones will work. A microphone generally needs a preamp.