Traktor + XDJ Aero Only 2-channel soundcard available

I have installed XDJ Aero driver on WIndows 8.1 according to this guide http://www.pioneerelectronics.com/ephox/StaticFiles/Manuals/DJ/XDJ-Aero%20Traktor%20Pro%202%20Guide.pdf
However, in Traktor preferences, I can't seem to find "PIONEER XDJ-AERO ASIO" device. There is "Line (PIONEER XDJ-AERO)" device in Traktor Audio Setup device list, but in Output routing I see that this device has only 2 channels available.
What should I do to get 4 output channels in Traktor?

My system: Lenovo Yoga 500 14IBD, Windows 8.1 64-bit,
Traktor 2.8.1 Demo version,
Aero driver v. 1.120 (I reproduced the problem with v 1.000 driver)

Would be very grateful for help.