If you want to improve things, I would recommend putting a reclocker like the Synchro-Mesh between your AppleTV and your Parasound P5. The reclocker would have Toslink in and then S/PDIF coax out (I can recommend a very good cable). This will reduce jitter from the AppleTV for TV and stereo, improving imaging, focus and soundstage width and height. About $600.
If you want to improve things even more, you might consider a dedicated server and USB converter. This is a lot more expensive, but will be better than the ATV. It would connect USB from the server to the USB converter and then coax to your P5. The reason for the USB converter is again to reduce jitter over what you would get directly out of the server. Good servers are generally thousands of dollars, as are good USB converters. You are looking at probably $4K to make a significant improvement.
A fairly inexpensive way to get both new server capability and low jitter is the Sonos reclocked with a Synchro-Mesh. $1000-2000, depending on options.
Steve N.
Empirical Audio