That’s like comparing cameras based on the amount of megapixels. Marketing terms taken from tehnical specs that offer little real world information about quality or performance.
One informed user posted a review of MC3000 controller that perfectly indicated why you get good sound quality from denon gear (LONG READ):
I’m really disappointed by the lack of attention sound quality is given in reviews - I’d love half a review to be purely on the colouring, like reviews of amplifiers or speakers. Sometimes (and I’m not commenting on your point makar1, just chewing the fat), DJ reviews just cite the resolution and frequency (“this is 48khz/24bit so is as good as it gets”). This is like evaluating a car by stating how high the speedometer goes. In my opinion sound quality is the invisible elephant in the room that no-one realizes affects them.
He later compared S4 with MC3000 based on his experience:
Additionally, because of the independent power source and the analogue internals, the mixer is unphased if you unplug the laptop while feeding an audio signal through one of its analogue lines. Having the digital technology as auxiliary to the analogue audio functionality that is central to this mixer seems a major engineering strength. Like all good audio equipment, you run this mixer hot to get the best sound out of it. The beautiful, silky rich bass reminds me of my best Vestax mixers. You can hear Denon’s heritage in the engineering immediately. It is also built like a tank.
The MC3000 does more than passthrough, it contains active analogue circuitry on both non-digital channels, and plugging in the adaptor does not change the output levels - you can do it mid-mix - just the lights become brighter. Read up on input and output impedance and noise/interference, and you will understand how output power affects sound quality. Or just plug the two into a non-studio desk and hear the difference (because non-studio desks have a lower input impedance), or run the signal through a long cable (because with lower levels the noise level is relatively higher, so amplification amplifies the noise by more).
But I often struggled to get a good punchy clean sound when connecting the S4 into soggy desks or amps, whereas I never struggle with the MC3000. My theory about it being impedance is because they were pretty much peers when feeding decent desks, but the S4 degraded when feeding poor desks or the junk you often connect to at parties; and because the levels coming from the Denon were astronomically higher. I wasn’t surprised that something running with 10 times the power supply would have a lower output impedance.
However I also appreciate what might be the colouring of the Denon. I work a lot with my KRK8s, which have a very club, punchy, crisp, solid but controlled sound - good, wide-spectrum kicks or live drums with some crunch in their distortion come through in every bit of their glory. The Denon really excels at this sound when pushed right - the separation and staging is phenomenal, and there’s always plenty of energy but it is immaculately precise and restrained. It reminds me of the Vestax scratch mixers - they were heavy beasts and you could push them, even mixing sloppily into the red, and the kicks would just sound fuller and even more gorgeous, and the rest would stay just as crisp, hence my love of engineering with the Denons - it is plug n play. The S4 was a clinical sound, certainly precise, but with poorer quality output stages there wasn’t the separation in the mids - they’d start to feel clouded and a little gutless. I’d also say the Denon specs don’t do the machine credit. Still now, a good few years after buying the Denon, if I don’t use it for a few weeks and come back the sound is exhilarating. Again, this might be colouring as well as tech sheet specs.