Alt AULab link, without the requirement of an Apple ID to download: https://www.apple.com/ca/itunes/mastered-for-itunes/
It's quality software but a bit unintuitive how to set this up. First you create virtual audio source in loopback then with audio hijack you can route adjusted audio to this source you can't route to normal outputs. Also you need to have hijack turned on "record" for the effects to work.
But after that it works pretty well and you can add pretty cool things like... you can record both raw input and procesed input and route to your destination at the same time. Or you can mix in other apps like music into recording/routing.
Sidenote I've also tried BlackHole and unfortunately didn't have too much luck with it. It somehow worked as Loopback alternative but i think Loopback / Hijack share same audio drivers/code so integration seems smoother.
Here's a crude diagram that shows how this might work:
+--------------------------------------------------------------------------------------+
| Loopback: virtual_keyboard |
| |
| +-------------------+ +-----------------------+ +--------------------------+ |
| |MIDI / Logic piano | |output channels: L & R | | monitors: headphones | |
| | (Pass+Thru) +----->+ +--->+ | |
| +-------------------+ +-----------------------+ +--------------------------+ |
+--------------------------------------------------------------------------------------+
+---------------------------------+
| Zoom |
| +---------------------------+ |
| | input: virtual_keyboard | |
| | | |
| +---------------------------+ |
+---------------------------------+
I believe this would reduce the latency from your keyboard to your monitors while any lag Zoom has processing the audio (and probably) video would be slightly increased.I don't know of free, good alternatives.
Paid: Loopback, Audio Hijack, Sound Siphon