Eurorack, Steve’s MS 22, and all your fantasies of a Korg MS 20 like filter solved.
I also have an aisynthesis OTA that I built as a DIY kit, but it is not as screaming as the MS 22.
I do love my Pro 3 filters, but I agree a 4th low pass (and 5th high pass) MS20 like filter would have been a killer addition to an already amazing synth.