Reply to Question about cueing/soundcard with APC40 and Trakor Pro 2 mapping

Sorry if this is a stupid newb question, but I recently picked up an APC40 that I admit I've hardly touched yet (and I'm new to Ableton, too.) I originally got it to produce dub reggae, but I'm really interested in getting Traktor Pro 2 and mapping the APC40 to it so that I can also DJ with it that way, like many of you are doing, rather than strictly Ableton DJing or buying another controller. I haven't studied it yet, but I'm wondering if there are any issues with cueing tracks (in headphones) with the APC40 mapped to Traktor and/or any other soundcard issues. Traktor Pro 2 is online for digital download for $89, but you can get the Audio 2 soundcard which includes TP2 for thirty bucks more at $119. Maybe having two soundcards wouldn't even work (the Audio 2 not being able to "override" the APC's or whatnot) but if it's better solution to get the Audio 2, of course, I'll do that. Thanks in advance for forgiving my ignorance.