[1150Post]

Oky, had a little free time this morning to examine the situation more closely. Seems that my Setups>Peripherals>Synchronization - Minimum Sync Delay for the Sync I/O was set to the same amount as my preroll under the Machine Control tab. This meant that Pro Tools wouldn't even consider playing till that 150 frames ahad passed. I've since set it to 30 frames, and now the system starts playing audio as soon as it locks.

Now I only get an audible stutter or blip at the insert inpoint, although the outpoint is clean as a whistle, but perhaps that's another thread...

Thanks for all of the help.