Yes, you can with the Gen 2 Turtlebox! You can use the Turtlebox like a PA for announcements, etc.  Also, the microphone input works while you use Bluetooth to play music, so feel free to get the karaoke going to take the party to that next level!  Even better, you can pair two Turtleboxes in stereo and plug a mic into each one for duets.

We have tested this Audio Technica microphone and it works really well with the Turtlebox:

Please note that it's not possible to adjust the volume of the microphone separately, just the overall volume of the speaker. To control mic volume, you will need a mic with independent volume control.