it's not only a matter of audio.. when audio is flanging also any virtual instruments you have in core audio will start +- 200 samples every time you press play, you will loose accuracy even between core audio tracks and core audio virtual instruments!! i hear this difference a lot, i use a sidechain compressor on the bass drum and i can hear well every little change, i like managing every delay manually, no delay compensation, and i want that every time i press play it sounds exactly the same as last time. Anyway as i said remove any tdm tracks exstdm and esb and core audio will be back synced again, hope they will fix it one day so we will be able to use again esb togheter with core audio.