Hullo

Just wondering what the difference between delay(ms) and block size is in the Audio prefs.

Any there exclusive, or does one override the other...I can't seem to find any documentation for it

cheers

...or is this the control block size?

Block size refers to how many samples each objects works with in turn. One audio object will process a block (64 by default) and then pass those processed samples to the next object. It's basically like a buffer between objects.

The delay setting is the size of the buffer to and from the audio interface, and it should always be bigger than the block size. I think most audio interfaces won't go below 64, anyway. If you use jack, the buffer size there overrides the delay setting in Pd.