I got an HX Stomp a couple of weeks ago and am running it into the fx return of my Markbass LM2 and 2 Markbass 2x10 cabs. I don’t use any cab sims, but with Preamp or Amp sims it sounds great. I’ve also been experimenting with the 4 cable method, so I can incorporate the Markbass preamp section into the chain, either in place of one of the simulated preamps/amps, or run in parallel. I’ve had great results so far, not only with bass amp sims but also with many of the guitar amps, as long as they are tweaked to taste. I believe the Markbass set up is relatively transparent so the character of the different simulated amps (eg SVT, GK800, Bassman etc) shine through and significantly alter the tone of my rig. As someone has mentioned above, if you have a very colored bass amp setup it might not be so successful. I’ve yet to try the HX Stomp setup at a gig or band rehearsal yet (due to obvious quarantine reasons), so I haven’t been cranking the volume too much but I’m hopeful it will work out!