My favorite (affordable) rack unit is a good compressor/limiter/gate. I have a Peavey Cel 2 that cleaned up and level things nicely, but it wasn't the one with the hi pass. To me a good high pass can make or break everything. The Daking Mic Pre One was pretty incredible with the Eleven Rack. If it got too boomy, I'd move the high pass and nothing would change except he removal of boomy frequencies. The lows would still "be there" though and not thin anything out. The best thing about it was that as I have described it to others, you don't even need to double guitars to get a huge sound because it's like having about 10 tracks of guitar all at once. The Trident circuitry also took out a lot of the wishy washy digital noises and the effects are more "solid" so you don't need to really have anything special. I've been thinking about getting another one, but I'm pretty happy with the circuitry that is captured in the Ownhammer impulses through the EPSi. I wish they would do some Trident flavored IR mixes though. I don't think you can really emulate it though because I had some impulses of mic pres and they don't seem to have that special something that is in the real thing. You can definitely get good sound with some work, but the Mic Pre One made pretty much everything work, even the stock presets of Eleven Rack with no adjusting.
I tried an experiment with a Behringer VT999 and swapping to a Tung Sol tube which also made the stock presets come to life. Not quite in the same way, but there's a lot of interesting ways to get sounds, that's for sure.
Enabling the Resonation feature on Eleven Rack and plugging a cable into the front Output to amp also for me took away the need for the DBX compressor (The Peavey Cel 2 has similar circuitry as the DBX). Depends on what you're going for, but was easier to get something close to the DBX with the resonation on and recording direct with that little trick.