Yes, you can turn the copying off in iTunes, but I find it showing up in iTunes at all quite a pain.

What you can do instead, is go to Finder, and navigate to a .m4a, and choose Get Info. In the Get Info panel, choose Open With "Quicktime Player". Then click the button that says "Change All". Then when you audition in BIAB, the file will just show up in a little black Quicktime player.

That said, BIAB really should just play the audition from the BIAB app like every other sample playing app. Also, we should be able to audition variations as well, and do this rapidly. I have Maschine and auditioning sounds is so fast and easy, and in BIAB my biggest obstacle is finding the right sounds... so painful, and getting worse with the growing loop library. I've been tempted to cut up all the audio files into variations, and load them all into a Maschine Library just so I can find things fast...