Does anyone have dual sound cards working with android?

ANDROID 6.0.1, paid version DJ2

Both sound cards work, but DJ2 only talks to one card or the other. I have an onboard and a second soundblaster USB attached via an OTG cable. I do NOT want “split outputs” with mono via the Y cable.

Is there something I have to do in Android to allow DJ2 to use them both? Developer USB options set to Audio.

Natively both sound cards work as outputs (onboard or USB) as an either/or. When USB sound card is playing, and I plug in my onboard headphone to cue, the main USB stops working and it switches the main to headphone.

Spit output works on both onboard and USB. Meaning it plays left and right cue on both onboard or on USB, but not both.

Lenovo A12 Yoga Tablet (Intel Atom CPU, 2GB ram)