Comment 25 for bug 1310260

If the radeon driver is the problem and the intel one works, then just disabling the radeon hdmi card would be a better workaround, i e, in your case:

options snd-hda-intel enable=1,1,0

Vga-switcheroo cards are quite unusual so I don't have much experience with those. Does the above work for you (as long as you keep the radeon GPU disabled)?