Trifield is absolutely excellent.

I personally wouldn’t use the 568.2 in this way, I would ditch the NAD and Dirac just let the 568 just do the whole lot, you might be surprised how good it sounds. Just get your speaker/sub placement right and possibly look at some physical room treatments if you are worried about bass issues. Give it a try both ways for a few weeks and see what you think. The 568 is a very, very good DAC.

Meridian also make processors which include their own room correction, MRC, which is transparent and designed to work seamlessly with Trifield processing, if you really do end up needing some digital correction.

HC: 861v4/ID40/LPS, DSP5000, DSP5000VC, DSP3100, SW1600, HD621, Oppo BDP-105, Sony VPL-HW55ES
2-Channel: Oppo BDP-105, TEAC VRDS-7/Trichord Clock 3/PSU, 551, Quad 303, Harbeth Compact 7ES-3, Kimber cables, Russ Andrews mains and supports.
Previous Meridian: 5000C, 5200SL, 7200.2, 6000, 562V.2, 568.2mm, 800v4, 808.2i, 818v2/v3, 861v8, 502