Problem with pre-cuing: master on USB device, Headphone on mac internal mini-jack.

Since 6 mounths I can’t use precuing.

Before there was no problem: Master on an “USB ext DAC” and Pre-cue on “Internal mac mini-jack out-put”.

Somebody can help me?

My config:
DJay 3.1.4
MacBook Pro 15’ 2,53Ghz
OS X 10.11.6

Thank you!