PLX-500 not visible Rekordbox

Hello,

Can't make Rekordbox work with my turntables.

Setup:

- DJM-250 MK2 + 2 x PLX-500 connected via phono, win10 and 3 devices connected via USB, ReKordbox + DVS 

- Sound drivers: all 3 units are there as Playback and Recording. I disabled the two turntables as playback.

Problem: I don' t see anything happening. No singal visible in Export or Performance.

I can record if phono switch is on, but I dont see any meter/.activity. I can also see the Calibration signal under Preferences/DVS if switch is on Computer,

a) Am I supposed to see the PLX-500 under "device" (bottom left column) ?

b) Am I supposed to use the phono switches on the DJM as Phono or as Computer ? (if as USB, blue circle light up but no signal, if as phono "External Input).