So, upon further review, I discovered that my version of SoundSource does include the parametric equalizer. However, it only works on the default audio device output, which can’t be changed easily in the MacOS system settings of Mojave. Luckily, some smart guy on the internet developed a script that can do it. I just pasted his code into the Script Editor program and modified two lines to reflect my hardware. Basically, I had to change the OS’ default from the default of internal speakers to my iFi iDSD Black Label DAC/Amp, which is of course connected via USB.
Here’s another screen shot:
Now I can use any # of PEQ presets from the AutoEQ project, including Headphone.com’s.
Cheers!