Hey all,
Long time lurker of many years, first-time poster.
I recently acquired a Mediatrix Audiotrix Pro (ATP for short) in order to test how good the card's Intelligent mode "faking" is through its sending of "ACK" messages. The card is supposedly brand new old stock. It seems to work well in Sound Blaster mode. However, when connecting it to my MT-32 and running DOS games configured for Roland I never see the MIDI message light up on the MT-32, and therefore no audio output from the MT-32. Strangely, many games will still play audio (Monkey Island 2, Indiana Jones FOL, etc) but I'm pretty sure they are falling back to SB or Ad Lib.

I am testing all this on my main retro PC which is: PC Chips mobo, AMD K6-2/500 with internal and external caches off (MT-32 is "old" so subject to buffer overflows, etc, so I'm crippling the system to make it more era-friendly), 256 MB RAM, 4 GB CF card for HDD running DOS 7.
I've tested the above configuration with my AWE64, and MIDI out works just fine (MIDI messages reach the MT-32 and audio output from MT-32 is good), so there's something funky going on with the ATP card which I am missing.
I also have an Audician32 card and so I have a full complement of the usual utilities installed for Creative Labs, OPL3SAX, and Mediatrix, should any non-Mediatrix utils be useful in testing.

The steps I've taken so far are:
1) Changed the ATP's board jumpers for the joystick configuration to be "Single joystick with MIDI" instead of the factory default which is "Dual joystick, no MIDI".
2) Confirmed that my game port->MIDI cable is working (using the AWE64 card I spoke about) and that my wiring is OK (MIDI "OUT" on game port/MIDI cable goes to MIDI IN on back of MT-32).
3) Checked the card's config using the SETUPPRO driver/config software for the Audiotrix Pro. This shows MPU-401 address is set to 330h with no IRQ set. SB is on IRQ7, DMA1 and address 220h.

Any help you can provide in my investigation is most appreciated !