My motherboard is a Gigabyte GA-H170-D3HP, which uses the Realtek HD Audio Manager. I'm on Windows 10 Education x64. I have both speakers and headphones plugged into my computer, and I only use one device at a time. I use nircmd to change the default device between the two and it works very well. The problem, however, is that the audio always plays out of the headphones regardless of which device is the default. If the headphones are the default then sound comes out only the headphones, but if speakers are the default then sound comes out both the speakers and the headphones.
How can I fix this so the audio comes out only the device I have set as the default? I would be fine with outright disabling the non-default device, but I can't find a way to do that via command line. The speakers are plugged into the motherboard, and the headphones are plugged into the front panel.
These are the two config screens in the Realtek utility. I can provide any additional information as needed.