DEQX is an Australian company founded in the mid-90s that makes very sophisticated room correction and digital EQ software that is used in black-box solutions as well as OEM speaker solutions such as Wasatch Audio Lab and NHT speakers.
Notable DEQX products include:
DEQX HDP-Express that does timing and frequecny response calculations
DEQX HDP-3 preamp
Edgar Kramer has a review for DEQX PDC-2.6P on 6moons.