You probably have, but weren't aware of it. I was for some time using a Sony player as a transport, whose digital output happened to end up failing and needing fixing. The first thing I noticed, a few hours before it failed and digital out muted, was a harsher sound that was only noticeable to me in two main areas, the voices quality and as though certain details were enhanced, things like the bowing on a double bass which became too noticeable. Those are sounds that once I've learned to spot, would make evident the type of connection I'm using, then knowing if I'm using a toslink or a coaxial connection. Maybe that difference in sound is not just because of jitter, however it's one of the few measurable parameters differentiating them.