With Martin's help (and Thái from Thorvin) I've been trying to set up the new lab machine's sound cards, now with some urgency after Eric G's report.
In Lab B it appeared as though I would need to make jumper adjustments on the audio network hub on each student station, but repeating the setup in Lab C I achieved similar results without changing the jumper...(?)
I have an email in to Thái right now regarding some remaining questions and will update this post when I know more.
The remaining issues revolve around the Sanako Duo recording streamed transfers. One concern is that it records to both channels during a stream from the teachers station (as in cassette, teacher-as-source and cd audio being transferred directly). Watching the transfer in "graph" mode on the SW I see that it goes to both student and program channels. If the student plays it back immediately after re-gaining control of the player they get a "echo-ey" effect - like pseudo stereo - that interferes with their ability to record their own voice.
Another issue is that each of the "transfer" streams ends up at the SW with a different recording level. Cassettes sound OK, but teacher-as-source is way too loud and CD audio is rather quiet. The recording level on the student microphone is also boosted when these transfers take place - almost as if there is some instruction coming from the TS that overrides the SW settings.