@ Johannes
In my tests, so I think it is a safer way to connect DJM 2000 mixer soundcard. If you must work at a private party and need to use CDs for any song that you not have in your computer. So I solved this dilemma with the following variant of the connection.
• DJM 2000/900 as sound card via a USB hub.
• Do my audio output option in the computer program to channel 2 and 3.
Even do the choise for external mixer, in the softwear setup.
• set the mixer on USB also on the mixer.
• CDJ Do i connect with USB to the hub.
And now even the phono cable, analog or digital channels 1 and 4.
• DJM 2000/900 on channel 1 and 4. Putt that on what you have connected your CDJ too.
• Then you choose DJM as sound cards.
You get automatic opportunity to be able to record your gig, without having to plug anything extra, in addition to this variant.
• Even with this setup you get the opportunity to be able to play CDs. While playing from the computer. When you intend to play CD disc so just press selection keys to CD. And when you want to return to the computer control in midi mode so you only press the selection keys on LINK.
And now, are you back for data / MIDI routing.