I love this mod but found the quack was not loud enough to be clearly and obviously heard over the music and other effects. I edited it myself to set the volume to 2.0 and this works great, but it might be worth considering adding a startup setting to allow players to more easily set their desired volume.

Yes. The problem is that Research Complete is in the Gui sound category. Because of the horrible sounds in the Gui, I have to move the sound slider to zero.
I really wish the one sound, with the help of this mod could be heard.
I have tried some sound mods to get rid of the horrible Gui sounds, but nothing works.
Edit: I miss this mod.

Added in v2.2! Added a startup setting; volume can now be adjusted up to whatever you want, set it to 100x you want that for some reason.

Thank you for your time and the new update. Will be awhile before I go back to v2.1 of Factorio. Found a major bug so I had to return to v2.0.
And currently able to adjust sounds, partially to my satisfaction to here the Duck sound.