I've done that.
Did the monitors version of that yesterday, had everything but the actual speakers turned on..
I do that a lot. My Sennheiser headphones have two jacks (one for the headphones and one for the mic), and both plug into a USB thing which contains some sort of built in soundcard. Sometimes I accidentally pull the jacks out of the USB part by a tiny amount, which makes the headphones simply not work.
I went to a store to retrieve my money for some headphones that were working, headphones that I bought because my old ones weren't working too.
I even got other model, more expensive, but same problem when I got home.
That's when I figured out that I was connecting it to the wrong entrance. Yep...
Mine has two connectors also. Sound and mic. At the beginning I found it confusing keeping track of which is which so I tied the mic connector to the cord as I'll probably never use it. I'm guessing most headphones have those two connectors.
Actually, only a minority does. Least in our country. Most have mic integrated to the headphones, so they need only one connector. However, it should be visible on the cord what belongs where, small headphones pictures mean headphone jack
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