DDJ-RZ.... Software mixer or Hardware?

Just curious, is the mixing in the DDJ-RZ done in the software or the hardware?

for example, is the audio actually running through the mixer and the eq's or is it a case of the hardware controlling the software?

When you turn the bass down, is that happening physically on the hardware or is it processed by the software?

Im curious because the built in effects of RekordBox are post fader, and I don't see how that is possible if the audio is being processed on that hardware.