First of all, you must actually have the soundfont.

You may download it here: http://www.synthfont.com/soundfonts.html
It'll be compressed as a .sfArk file, there's a download for the sfArk utility on the same page that will allow you to extract it.
Extract it to any location that you can easily find.

Next, you must install VirtualMIDISynth: http://coolsoft.altervista.org/en/virtualmidisynth
(I use version 1.17.1)

Install VirtualMIDISynth and it'll ask you to pick a soundfont - select the soundfont you just extracted. Click "OK".

Next, open up your DOSBox console and type in "mixer /listmidi". If "CoolSoft VirtualSynthMidi" is the new 0, it worked out well - otherwise, take note of what number it is and change your configuration file's "midiconfig" value to match the number.

This is the final step - go to each Quest for Glory folder for 1VGA, 3, and 4 and drag the "INSTALL.EXE" file onto any DOSBox executable. Change the music setting to General Midi Sound Device. Accept these changes.

Grats! You're now playing QFG on DOSBox with Fluid R3.

This also works for other soundfonts as well, as long as they're the .sf2 format. Enjoy!

(Note that as 1EGA and 2 do not support General Midi, the only way to play these games with Fluidsynth is to use ScummVM. I have also noted that for some reason, playing 1VGA on ScummVM using Fluidsynth will result in Erana's Peace not playing correctly - while playing it in DOSBox does. However, this may not occur for you, so you're free to try it out.)

Hello, just found your post and I want to try this for Quest for Glory 3, since ScummVM doesn't upscale properly, although it has midi support.
Which install.exe do you refer to and in which executable I should apply it to?

Thanx!

In the main game folder for Quest for Glory 1 VGA, titled "Quest for Glory (VGA)" there will be an "application" file simply labelled "INSTALL".

At the top of the folder should a folder labeled "DOSBOX". Open this in a separate window.

In that folder you will find another Application file labeled "DOSBox"

With these two windows (this one and the previous one) next to each other, drag INSTALL over to the other window and directly onto DOSBox.
Don't move the file, it should stay in the folder. If you accidentally move it, just drag it back into an empty spot in the previous folder.

It will then activate a program that allows you to change audio and video settings for the game.

EDIT: There are three other files named "Install", but you may ignore them. If your folder is organized alphabetically, the Application file will be the first one of the four.

https://i.imgur.com/HFEZ7e2.png

Here's a screenshot I took as an example.

ok, will try it this afternoon - thanx
Yesterday I installed both Quest for Glory 3 gog and ScummVM with FluidSynth and the midi music was better by far.

It worked like a charm, thanx a lot!
I uploaded a screenshot, hope it is the correct setting.
One last question: Do I have to run VirtualMidiSynth everytime before I run QfG3 or it is a one-time thing?
The only thing is that the program runs everytime I launch a game, any game. Any thoughts on this matter?

I feel like that behavior is normal. And VirtualMidiSynth should boot up automatically with your computer. I do think it's necessary, but take that statement with a grain of salt.