Smart CFX only works with Rekordbox as far as I know. You can map Neural Mix to the pads of the FLX4 by yourself. Mapping the Smartfader button to Crossfader FX on/off should be possible as well
As @Andreas_Haase1 stated, Smart CFX is a Rekordbox specific feature.
In my personal custom MIDI Mappings, I usually map SHIFT+Headphone Cue to the Neural Mix/EQ Toggle.
a. The MIDI command in djay is called Toggle Neural Mix - EQ and this toggles your controller EQ knobs between regular EQs and Neural Mix EQs.
Hi @martinschki, yes the Smart CFX button on the FLX4 is being used in the default djay Pro MIDI Mapping, but not in the exact same way as Rekorbox’s Smart CFX implementation. Since I don’t have a FLX4, I can’t tell you exactly what this does in djay, but perhaps one of our other users like @Michael_Wisniewski can chime in.