I calibrated to K20. A few things:
You have to consider the size of your room when setting a reference level. Maybe you have. Sound On Sound has a good article (bottom of linked page):
https://www.soundonsound.com/techniques … els?page=3
80dBC is borderline small concert level. By comparison, I've set mine to somewhere between high 60's and low 70s; I prefer it slightly on the quiet side. I know where I'm at though.
Secondly, All your faders should be at 0dB when you run your calibration. DAW, TMFX, any in-line mixers, etc. Everything unity. The only thing you should be adjusting is your pink noise and monitor gain.
The only thing the dip switch on BFPFS is for is to deliver your monitors an idealized level. Powered monitors, specifically ones like the Yamaha HS50 that I have, allow for a range of input signals to achieve a given volume. However, the knobs will give you the most adjustment if you have them near the center. If you use +4dBu into these monitors, you have to turn them all the way down. The knobs aren't that great so it makes it more challenging to dial in a precisely matched level in each one. -10dBV has been fantastic for me.
I don't worry about TMFX in this process. It should be doing nothing. If you want to shift K scales, I suggest you do it in an external monitor controller. Personally, I'm moving faders like crazy in TMFX and would hate to have to mentally adjust all the time. I just know where I need to be so I leave it at K20 and turn faders down if I have to, when listening to YouTube or mastering.