Is there a reg entry or other way I can increase the FM output through the toslink connector in Win98SE on my Fortissimo 1?

MIDI output slider, on the other hand needs to be decreased, otherwise it clips, so I don't think there is anything wrong with the port. And I see no FM volume output slider in the multimedia & sound applet.

I attached the sound level before and after normalizing from Doom 1 E2M2 to demonstrate how low the volume of the recording is.

I would like to get louder output only because I think the quality will be better.

I'm using the last VxD drivers from Guillemot and recording through ASIO on my Win10 PC.