A moment, please, while I vent my frustration with damned F*ING invisible characters! (This lopped off most of my post and I had to build it again. GRRRRRRRR...)
I'm getting the impression, from the tidbits of plain english I can read in the code of the Apple Audio Extension extension, that the various devices are supported by a plug-in architecture. This is what I'm basing my musings on as to whether or not we can transfer some later code back and patch it in. The file also has a number of "Joy!peffpwpc" headers dividing up the code (as with most other extensions). In case anyone was interested, here are a number of the device plug-in names I see in the file:
From a portion of the Data fork:
BurgundyPlugin
GCAwacsPlugin
DacaPlugin
USBAudioPlugin
VirtualHALPlugin
MLANAudioPlugin
DigitalSndPlugin
TumblerPlugin
SnapperPlugin
From a portion of the Resource fork:
DAVAudioPlugin
GCAwacsPlugin
I2SAudioPlugin
VirtualHALPlugin
SnapperPlugin
TumblerPlugin
ASPScalarPlugin
AltivecPlugin
Many of the above refer to specific motherboard integrated audio devices.
And here is a subsection of data from one of the plugins:
BurgundyPlugin
__SndHWSetPlaythrough
__SndHWSetSystemMute
__SndHWSetInputGain
__SndHWSetSystemVolume
__SndHWSetActiveOutput
__SndHWSetActiveInput
Here it appears to be declaring basic operating parameters/variables to the Sound control panel for the given device name. The extension mustn't be fully recognizing the Mini's sound device, "Toonie", and therefore never defining these parameters/variables. Presumably we can either steal functional code from a later driver/plug-in, or perhaps even hack an existing plug-in to be recognized as belonging to the "Toonie" by OF name/address.
This seems like a plausible explanation for the lack of controls or jack switch detection by the Sound control panel, given the evidence.