Well, it's much easier to test Wiz7 in the DOSBox because of unified environment. Especially as you said it doesn't work there too.
I'll test it.
...
And checked.
In "standard" DOSBox, surprisingly enough, the best combination is MT-32 (with ROMs in dir) for music and Speaker for FX. SB/Adlib/Covox SMII sounds identically, other two covoxes not sounds at all.
Thanks to eXo, we found "ideal" combination: DOSBOX-X with MT-32 (with ROMs) for music+SB for FX. Sounds just as Speaker, but clearer and without cut.
To tune that, you need to enter configuration from the main game menu. It's only place where sound and FX can be adjusted. Doesn't work when you actually started the game.