Split Input Channels Using SoundFlower and AULab

It could be done using Rogue Amoeba's Audio Hijack which is ostensibly an audio recorder but has really comprehensive routing capabilities too.

You build your path just by drag & drop, it makes the connections for you.

Route a source to two different Channels plugins, kill left in one & kill right in the other - that way each will pass only a single side of the stereo pair.
In front of that you put two EQ plugins, then route both to a single output, headphones/speakers etc.

It's fairly expensive for a one-trick pony, but it's extremely useful if you need the trick it can do.

I posted more examples on https://apple.stackexchange.com/a/203009/85275

BTW, remember to switch it on once you've built it ;-) Button bottom left goes white & the numbers go orange & start to count time.
As a side-effect, launching any specific Hijack preset will launch any apps assigned to it.