There is an app called AdjustDuo.exe in the install bundle which kind-of almost does an OK job, but so far I have had to hack duo.cfg on every chipset we've had.

Here's how:
1. Start Media Assistant (Duo) so that a temp.cfg file gets created.

2. Close Duo.

3. Rename Duo.exe to Duo.xxx to prevent it starting.

4. Open two instances of the Windows sound mixer; one for volume and one for recording. Make sure that all necessary volume/record controls are visible.
a) Start a program source in Lab 300 teacher's station and press the manual button.

b) Adjust playback line-in and main volumes on student station using the Windows mixer.

c) Select record line-in from the mixer and record the program with the Windows Sound

Recorder. Then mute the playback line-in and play the recording back and adjust

record line-in.

d) Stop program transfer by pressing the manual button.

5. Adjust playback mic sidetone level by speaking and listening your own voice.

6. Start a wav file with mediaplayer and adjust playback waveout.

7. Start a rmi file with mediaplayer and adjust playback midi.

8. Start a CD track and adjust playback CD audio.

9. Start Sound Recorder, record your speaking, play it back and adjust record mic accordingly.

10. Rename Media Assistant back to Duo.exe and launch it.

11. Rename temp.cfg to duo.cfg.

12. You can use this same file in Lab 300\Master folder by renaming it as Lab300.cfg

Further hacking can be done using the following guide:
The various sections of the duo.cfg file can be manually configured. Numeric values range from 0 - 65535. Duo must be shut down when editing this file.

[RECORD VOLUME] *Note that these are recording volumes. It is possible to have playback too loud during transfer, but too quiet when replayed from local disk.
LINEIN=5000 *sets the recording level for incoming audio.
MIC=50000 *sets the recording level for student generated files.

[PLAY VOLUME]
LINEIN=15000 *adjusts volume levels for incoming transfers (such as tapes and audio CDs)
MIC=5000 *adjusts student microphone sidetone volume when the student is in control
CD=26025 *adjusts volume of CDs played on the student station
MAIN=21000 *adjusts all volumes simultaneously.
WAVEOUT=20000 *sets volume of media files played back on the student station