I reassembled and powered it up again to check. On boot, the sound is configured as I described earlier, port 230h, IRQ 5 and DMA 0. This checked with ESSCFG and HWiNFO. There are no jumpers, it is all configured with ESSCFG, in my case version 1.9 (I can't remember where I got it from), which misdetects it as ESS1688. Thanks for the link to the ESSCFG meant for this sound chip, it wasn't available when I first set it up a few years ago. I'll have to transfer it to the HDD later to try.
Anyway, in this boot-up state, the master volume is configured as so you need ESSVOL /v:15 to set it to the max. Wave and synth volume were at 8, I left those alone. Wolf3D detects an AdLib and works fine; Monkey Island and Prince of Persia 1.0 will also detect an AdLib as long as the CPU L1 cache is disabled.
With ESSCFG, I can configure the port to the standard 220h and DMA to 1 (which shares it with the IrDA). Then with BLASTER set to A220 I5 D1 T4, Wolf3D will detect a Sound Blaster and work with PCM audio. wolfdosmpu will also work with the wavetable synth via MPU-401. Other games like the usual Doom, Heretic, Raptor, Quake, work fine too.
I'm not sure why yours isn't able to reconfigure the IRQ to 5. On mine, IRQ 9 is taken up by the TI CardBus controller, IRQ 7 by LPT1. Perhaps try disabling some devices in the BIOS setup to see if it assigns a different IRQ?