It seems that I spoke too soon. I have found out how to fix it, and the fix could work for BOTH the input and output issues.
If I edit the file 'com.apple.audio.DeviceSettings.plist' (located at /Library/Preferences/Audio/), find my device by its MAC address, and then change:
(*** NOTE: My sampling settings and such may be off, but they still work. Your mileage may vary. ***)
| <key>bits per channel</key> |
| <integer>16</integer> |
| <key>bytes per frame</key> |
| <integer>2</integer> |
| <key>bytes per packet</key> |
| <integer>2</integer> |
| <key>channels per frame</key> |
| <integer>1</integer> |
| <key>format flags</key> |
| <integer>20</integer> |
| <key>format id</key> |
| <integer>1819304813</integer> |
| <key>frames per packet</key> |
| <integer>1</integer> |
| <key>sample rate</key> |
| <real>8000</real> |
to:
| <key>bits per channel</key> |
| <integer>24</integer> |
| <key>bytes per frame</key> |
| <integer>8</integer> |
| <key>bytes per packet</key> |
| <integer>8</integer> |
| <key>channels per frame</key> |
| <integer>2</integer> |
| <key>format flags</key> |
| <integer>4</integer> |
| <key>format id</key> |
| <integer>1819304813</integer> |
| <key>frames per packet</key> |
| <integer>1</integer> |
| <key>sample rate</key> |
| <real>44100</real> |
Then, launch Audio MIDI Setup and you'll see that you have your two channels back 🙂
No need to restart or anything!