Long Coaxial audio run?

So much loss of quality even though it would be a digital signal to the DAC?

The benchmark DAC1 claims to be able to work with a 1000 feet of Cat 5 cable but that is the only one I have seen making such claims. Any digital interface seems to suffer from jitter and longer runs are worse. It can vary from barely audible or subtle to plain bad and each situation is different so it is hard to predict. Good power conditioning seems to help. You need a reclocker or get a DAC that you think can handle it....and test it thoroughly by A/B short versus long runs to satisfy yourself it is doing its job.

Is USB effected by all this "Jitter" for example a laptop connected to a USB Dac with like a 15 foot USB Cable etc…?

No it should not be - USB is sending "data" without a timing signal.

Jitter has no affect on data. You can copy a CD a million times - it does not matter.

Jitter occurs when A to D or D to A is occuring. Digital works wonderfully provided timing is VERY accurate (or erros are randomized).

Unfortunately maintaining a precise clock over interfaces is not easy - it is much better to do it all on one chip with crystal clock close to the converter. However, the reason for passing a clock signal along a digital audio chain is to maintain the relative timing of the devices. This is so nothing gets too far ahead or too far behind....if for example the DAC got too far ahead then it would end up having no data and music would stop. If a DAC gets too far behind then all the "bits" need to be temporarily stored somewhere in a buffer. Also if you are watching a DVD with video then you want the sound to stay in sync with the video - so relative timing is often important.

With A USB connection the devices can "handshake" - data is sent or resent upon request so buffers do not overfill and no data is lost and no synchronization is needed.

Your only concern with USB is the jitter quality in the DAC device itself. (Note that USB protocols and communications will have periodic bursts and some data packest will be repetive - so there is still a risk that correlated noise from USB communications (and the draw on the shared power supply) reaches the DAC clock...

Undertow,

Yes and No. In theory Yes. In practice sometimes NO - as the bursts required for USB operation may feedback through the power supply to make the DAC inside the USB device more jittery than an equivalent AES/EBU or Toslink setup. Unfortunately activities close to the DAC itself can affect jitter. It is the same problem in a CD transport...control signals to the servo motor may end up inducing jitter in the DAC clock.

Remember that Toslink and Digital coax have been around longer than USB and therefore DAC designers have had a bit more time to work out all the possible jitter issues and good ways to attenuate them. In that sense a USB communications protocol running off the same power supply might be an added "unknown".

Undertow,

I think you are right on. I use five megachangers to feed a DAC for a total cost that is still way less than that of a high end player. The sound is probably 9/10ths as good but most important is that I get to hear my music instead of fighting with jewel cases and a filing system (now where is that CD?). When you have over a thousand CD's it is nice to be able to cue any one of them up at the push of a button for contiinuous play. So I am with you there and would not recommend going for an extremely expensive high end player. One day I will junk the tranports and connect the DAC straight to a PC where my music will eventually be stored - that, my friend, like it or not, is the future!