Could someone please help me with getting Frederik Pohl's Gateway to run together with SOFTMPU?

I've got two ISA cards - Soundblaster 16 CT2940 and Yamaha YMF based one that I'm using only for its bugfree MPU interface. Right now I'm trying to get MT32 music from the game.

I'm booting into pure dos. To initialize the Yamaha card, I'm using Tiido's SETYMF utility. (to be clear, its own SETUPSA gets the same result). I'm puting the MPU interface to IRQ9, port 330. I've also disabled ACPI just to be sure. Then I launch SOFTMPU with /MPU:330 and /IRQ:9

After that I'm launching the game with MT32 9 330 parameters. It loads up, sends midi commands (I see the blinking light on Roland's USB midi interface) and MUNT on another PC running inside Falconsoft Midiplayer shows me MT32 messages (first "GATEWAY", then "LEGEND ENTERTAINMENT - GATEWAY") but that's all. When there is music should be playing it's silent. No midi commands being sent. Midiplayer also shows that there's nothing received during gameplay. Only when I type "QUIT" in the game to close it and confirm exit, the game sends another message to MT32 ("GATEWAY") and closes.

it behaves the same if I launch it with MT32 2 330. Does anyone know what the problem could be here? I've looked arount SoftMPU forums here and only thing I could find is that someone posts SoftMPU itself to get around the same problem, but that was in 2014 and if I understand correclty, it should've been fixed in the latest SoftMPU version. Am I missing something?

Thanks in advance!

Edit: forgot to add that the system is in my signature - SLOT1 440BX motherboard with VIA C3