I do thank you both for the help, but this cantabile/voicemeter stuff just seems far too complicated for me.
I will post this in case anyone else has this issue and wants a super simple solution.
You will need four free programs: VB Audio Cable, LoudMax.dll (a limiter), Audio Router, and VSTHost.
Use Audio Router to route your audio (from wherever you please) to the VB Audio Cable.
In VSTHost, drag LoudMax.dll (from an explorer window) onto the interface and it will connect to the input and output, creating a new little box
Click the device menu, then click wave, set input to VB Audio Cable, set output to wherever you want the sound to go. Then experiment to find the lowest sample rate you can use without the sound breaking up.
That’s it! Just click on the white circle with the red line on the green background on the LoudMax’s little box to open it’s interface. Set both sliders to the volume limit you like and there you go.