clocking, sample rates
on the back of the ADA800 there is a sliding selector next to the power cord. right? the options are 44.1, 48 and ADAT. Might be more that i forget, but those are the applicable ones. You have have a couple of options here.
If you track all your projects at the same sample rate, you can select that sample rate on the back of the ADA8000, then in the hardware setups window in protools, (under windows) there is a box called "Clock Source." In this case, select ADAT optical as your clock source.
If you change your sample rates and/or (like me) trust the digi's clock more than the behringer's.... Then you need to have an optical cable running from the digi's optical out to the ADA8000. Then you move the slider on the back of the ultragain to ADAT optical. Then in the hardware setups window as above, select "internal" as the clock source. That should make the clicking stop.
Also make sure the optical cable is really, really securely plugged in. I had a faulty connection once. You have to push harder then you expect to really get it in there.
good luck
saburo