I often switch between speakers and headphones by using a program called SoundSwitch to swap which device is the default audio device. Unfortunately, AudioRelay does not have an option to use the Windows Default Audio Device, so I have to manually swap which audio is being sent in AudioRelay. Compare this to Discord, for example, where the sound outputs to my speakers or my headphones, dependent on which is the current default, with no intervention on my part.
Please add the ability to select the system default audio device, in addition to the current options.