dac with sonos

What does jitter sound like? How can you tell if what you're hearing (that you don't like) is bad source, bad cable, tube problem, jitter, or misaligned stars? (Ok, j/k on the last one). Since going to digital, I hear what I consider harshness and lack of dynamics. Is that caused by jitter?

Thanks Shazam. Like I said, I'm new to the digital bit (other than the Rega Planet CD player I purchased a thousand years ago--and still use, I might add). If I understand correctly, the Sonos player has a DAC in it, it's just not very good, correct? But some folks seem to be adding additional bits between the Sonos player and an outboard DAC. That's where I start to get confused. Also, is there general agreement on which way is best to connect a DAC (optical, coax, or toslink, etc.)?

THANK YOU!