Y'know, I'm not jazzed on the Quadrax, either. I thought that Intellijel had the formula right with the Quadra, which you could use on its own just as four two-stage EGs, or you could couple the Expander with it. That arrangement gave you CV over either rise OR fall, not a single CV input for both, plus you had a few other tricks there that don't seem to have made it to the Quadrax. Yeah, it's a simpler module, but not everyone wants (or needs!) simpler.
Gonna fix this compressor thing right now, too. Don't put it IN the cab. Instead, what you want is THIS: https://fmraudio.com/products.html That's right...not one, not two, but THREE excellent pro-grade choices in a tiny, inobtrusive 1/3-rackspace box. While the RNC might be the one that jumps out at you, the REAL solution is the RNLA, which works less like a VCA compressor and more like an opto limiter, like the LA-2A and, more recently, the ART ProVLA (which I should note that I have TWO of, because they kick ass!). It 'smooths' out the peaks, but allows you to go up to your threshold while banging away furiously, then it adds a nice bit of color once you cross it. This should work MUCH better than most affordable Eurorack compressor modules while still not being a huge thing that takes up space.