From my experiences with mixers prior to COVID disrupting my ability to recreationally listen to music and taking my memory with a grain of salt…
MP2015 for precision and transparency, equaled apparently only by the analog Iso420 in tests. It’s a strange level of clarity, with only a tiny bit of boost in contrast and detail over what you pipe in. Amazing considering it’s got almost as much group delay phase distortion on its iso channel tone controls as the X1700 and DB4’s ‘iso’ mode.
X1700 for euphonic loveliness almost too good to even bother DJing with instead of listening.
Then I’d probably clump the d.4, DJM-900NXS2, and DB4 all about in the same league, though I’m probably partial to the DACs in the master/record sections of the DB4 compared to the DJM. I’m weird, though, because I don’t even think the DJM-800 sounds that bad if you bypass the ADCs on it. These other mixers may sound more realistic at times than the DJM-900NXS2 that can sound too sweet & synthetic.
I’m not a big fan of the newer analog Xones’ sound. I mean, they’re fun to play on, but not actually that hi-fi, though I liked the old 62 with the EQs bypassed and using the top aux system to mix on rotary-style. I keep buying those, then sell them when I compare another to one of the digital mixers yet again. Any analog mixer might be a good match to muss up the SC6000’s intermodulation distortion harmonics, though.
I also have not been unimpressed by the new V10’s sound, but I think it’s got some weird design choices unrelated to sound. It’s also basically a gain structure for the ADC section that departs from older Pioneers and is now like everyone else. They finally figured out a good way to do the metering feedback on the NXS2 and the Tour1 with their old variable analog input gain structure, and then they abandoned it to instead just do fixed analog input gain.
I did think the X18xx series mixer have improved a little on their sound processing compared to their release, but my ears are so weird now it’s hard for my to say with much certainty beyond that. I recall them being more like an analog mixer’s mush than something like the MP2015 in-the-blend, though, and I certainly never considered the new Denons edgy. Maybe a little hard & coarse up top compared to original input, tighter rather than bloomy in the kick, narrower in the lower mids’ stereo, grainy, restrained, constrained, and occasionally like the sound was being squeezed through a tiny hole originally, but that last attribute especially seemed reduced in updates some. The X1800 always tested fine, though.