DDJ-FLX4 with an external soundcard want to switch a deck to audio THRU

Hello Pioneer,

I have a DDJ-FLX4 with an external soundcard want to switch a deck to audio THRU.

I also have Pioneer RMX-1000 which is what I am trying to play thru audio thru deck. 

How can I have this feature? 

I already set the DVS enable and I do not see the option to switch from internal to THRU as I read mentioned in forums previously.

Thanks ina dvance for your assistance.

Kind Regards,

Ricardo Arguelles