The sound of the AUX doesn't work


This obviously means it’s not just the AKG’s causing the problem.
If you haven’t tried it yet - have you tried this yet? - then updating (or rolling back) the driver of the device powering your AUX input, seems worth a try.
I copy-pasted these instructions from another thread (just make sure you edit the right device):
Perhaps you could also try updating the drivers of the device that doesn’t connect - but, please be aware, this usually carries some risks, so you’ll be doing this at your own peril.
You can update drivers through Windows Update, or - in this case, preferably - in Device Manager, by going to the “Sound, Video and Game Controllers” tab, right-clicking on the device, selecting “Update driver,” and letting your machine search for driver updates automatically.
If the results of the operation turn out to be disappointing, you can roll back the driver through Device Manager, in the device’s Properties tab.
Here’s the how-to on the update process:

And here’s the how-to on the roll-back process:

Feel free to post back with your results if you decide to do this.