iPhone 16 Pro aux connect will not work

It's pretty difficult to try to diagnose the issue and offer suggestions without full details. Presuming that your iPhone is up to date with iOS updates and that you've tried restarting it, all I can suggest is trying a different cable, and if that doesn't work find another set of USB speakers to test with. That would help isolate the problem to either your iPhone, the cable, or the studio's speakers.

Regards.

I presume you mean the USB-C connector. What cable or adapter (brand and model) are you trying to use, and to what device/speakers and how are you connecting?