I blew up my nanoSHARC recently which was a sad day, the DDRC-88D is not quite a drop-in replacement for the now-discontinued nanoSHARC, but I am really impressed so far.
The nanoSHARC ran filtering at 96khz, whereas the DDRC is 48khz only. I was a bit worried about that. I suspect that miniDSP did that to allow for more FIR taps for DIRAC processing.
I have not noticed the drop in internal sample rate affect the sound quality at all. But, I will say that the DIRAC processing has been simpler than performing FIR correction on separate outputs as I was doing on the nanoSHARC.
The unit is aimed at the 5.1 or 7.1 market but it is suitable for up to 2 x 4 way speaker active crossover. I am using it for a pair of 3 way speakers.
The unit in my setup takes digital (CD quality and 96khz/24 bit) from a DAP over SPDIF and then outputs to 3 Khadas Tone Boards, again via SPDIF.
Pretty easy to configure a crossover, I had used the nanoSHARC before and the DDRC-88BM plugin is similar.
DIRAC is a different software tool for measurement, which is a bit frustrating, but it has worked for me OK.
Overall really happy. Going to try and see if I can use different configurations (up to 4 configs) to allow me to cycle through the 4 SPDIF inputs. That would allow me to use it as a 4 input digital preamp, and switch between DAP and my ADC from my turntable. I am fairly sure that will work, but if not, then I will have to purchase some kind of SPDIF switcher.
The only pain is that all the SPDIF connections are BNC. I looked at getting a different Tascam style 25 pin connector with RCA plugs, but that wasn't cheap. Some BNC to RCA plugs solved the problem in the end.
If you are going to use this in a home audio scenario, then make sure you get the SPDIF version if you have SPDIF level kit. The AES/EBU version does run at higher signal voltages IIRC.