Its always hard to tell whether the patch cord that you replaced was defective or if the sender and receiver had a timing problem on one kind of interface but not over the other. That said, clicks and pops shouldn't happen under normal circumstances.

I feed my Outlaw 990 over coax from my Denon 3910 and optical from my Sony SAT-HD200 DTV/satellite receiver. I switched the inputs and couldn't generate any clicks on DTV, satellite, CD, or DVD. I use analog out for SACD and DVD-A so I couldn't test them.

I agree with everyone's thinking that clicks shouldn't be....but can't add much that will help. In my system, however, kind of input doesn't seem to matter. Everyone says Outlaw is very helpful. Let us know what they say.