Coutts,
As a newcomer to this development, it occurred to me that maybe a different approach to the audio issues might be helpful. I'm not a programmer, so if this is off the mark, please ignore this post.
The T1i, without ML, naturally ports audio through the usb using a closed circuit that disables the speaker. For ML users (and folks that add the external mic input), it seems that what is important is added audio meters, audio triggering (enabled by the audio meters), and agc disabling. And, of those, the most important being agc disabling. If only meters and agc control are added, then the camera can do what it does naturally, audio usb out.
I realize that his does not address the live audio monitoring, certainly an important addition. My only thought was that whatever is disabling the playback audio, might be interfering with the real-time as well.
An over simplification for a complex problem, I know. Thanks again for your work.