Thanks for the mini review Mark. Your findings seem to tally with others I've read on these particular DSP boxes.
Just out of interest, would you be able to list the crossover points you use with all your speakers and subs and where in all that you've put the DSP boxes? It would just help me to understand your setup a bit better. Cheers.
Source: Apple TV 4K - DAC: Beresford Bushmaster Mk II - Preamp: CI AudioPLC-1 Mk II - Power Amps: Musical Fidelity 550K mono blocks - Speakers: Wharfedale Opus 3 - Cables: Mark Grant etc - Misc: Belkin PF30 mains filters.