There's an audio in hole on the front that it says in the maual you can use to play music from another device (like MP3 player, etc.) and run it through the boomox speakers. Also, there is a hole in the back to plug in earphones. That's it. Hope this helps you.
It has an audio input hole on the front and a place on the back where you can plug in earphones. That's all I see on it and there's no mention of anything in the small manual that came with it. It said something about you could plug in an MP3 player, etc. to the audio in hole and play your music through the boom box speakers.
The "audio in" jack will take a microphone, as long as it has the same 3.5mm mini stereo jack size (same size as the ear phones for an iphone) Headphone (audio) out is for listening with headphones or earphones. The audio in jack is for using a microphone to record things onto tape, or to connect your MP3 player or iPod to the box to listen out of its much better speakers.
All I have seen is a headphone out, and a "headphone jack" in. If your microphone had the same jack as a headphone, than i think you would be able to plug it in, but would be unable to play a cassette or cd at the same time as the mic