How can I check my line-in does work (MBP late 2010)?

Question

How can I check my line-in does work?

I'm interesting what software should I use and how.

It is MBP, late 2010. I do have an external working mic.

Answer 1

1. Launch System Preferences… from the Apple menu.
2. Click on Speech.
3. The left tab is marked Speech Recognition.
4. Set the Microphone from the default "Internal microphone" to "Line In".
5. Click on the Calibrate button. Then speak the phrases on the left e.g. "What Time Is It?"

If your Mac detects your line-in, you'll see the blue-green-red indicator respond to the volume of your voice from the line-in.

Have fun, and don't forget to mark the question as answered when you're done. Cheers.

Answer 2

You could try using LineIn.app from rogueamoeba. It allows to pass-through audio from line-in to speakers (normally disabled in Mac OS X). I did use this app quite a few times to play music from external source. Should do the trick for you.