Keef,
Its been a while since I've done batch scripting, ever since the advent of PowerShell I've found that to be much better in the rare events I find myself writing scripts on Windows.
I'm taking a stab in the dark here..... but how about replacing
Code:
h:
cd H:\ToggleAudio\
toggle-audio-7.exe
with
Code:
start "ToggleAudio" /d "H:\ToggleAudio\" /wait toggle-audio-7.exe
(you might possibly need to spec the full path for the exe rather than the prog name, I can't remember).
A quick Googoo also suggests there may be alternate means to achieve your goal if you can't get the exe method working....
Toggle set default audio device in Windows 7. - Scripts - AutoHotkey Community and
Windows 7 Tip: How to change the default audio device with a hotkey