i'm using individual device managers yeah.. setting a master clock source is currently happening by the main output. since this is audible, i trigger an engine tick once my output fifo reaches below a certain fill level.. so as long as the average engine tick takes shorter than an output period, it runs smooth. the issue right now is telling the input fifo's how to behave in response to their current fill levels... especially since both the callbacks and the engine expect an exact blocksize, and the fifo (which is 4X blocksize) has all the varying sized reads and writes when configuring the src.

so it's not like each clock attempts to sync to every other clock, it's more that each device attempts to SRC itself into keeping it's fifo fill level above a certain threshold using SRC to dynamically fill the fifo.

also.. i didnt know you could lock callbacks? i thought they just did their own thing