The Tanzbar and the comb filter really do work well together.
As far as tone suck, since I started using defaut values for input, AMP volume and track volume, and brought the main output volume up to +12 (which should give you unity gain from inputs to outputs on thru machines but ith some track headroom left in case you need to turn something up in the mix), and then started recording everything a bit hotter than the manual recommends (up into the orange on the LEDs, not worrying about goign into the red regularly but not pinning it in the red) I’ve had much better results. It colors the sound but it’s at least as good as the old MOTU 828 I used to use and once you get a feel for the weird gainstaging it really is possible to make it sound pretty good.
This is with a MKI, with a MKII you should have a lot more headroom to work with on the inputs and can probably get slightly better results than I do, but it definitely takes some work to figure it out. I usually do that sort of thing by ear but with the OT I really did end up having to go through the gainstaging threads and figuring some stuff out on my own and generally being a bit methodical about learning how to get consistent good results with thru machines and sampling from inputs.
Also, I know I keep bringing it up but learning how to set up a send track successfully made a huge difference for me, even a tiny bit of send reverb on all tracks makes everything sit together much better and sound a lot more finished. Using Dark Reverb and adjusting the low cut filter on it to keep the lows from getting too muddy works really well. Plus, setting up a send means you can mute tracks and still get a reverb (or delay) tail from the send track.