How important are transports?

Jeff_jones - No, It is not the AC power "pollution". It is generally the jitter spectrum that varies from one transport to the next and the edge-rate of the S/PDIF signal, as well as the impedance mismatch. I have found lots of transport S/PDIF outputs that are not even remotely matched to 75 ohms characteristic impedance.

Steve N.
Empirical Audio
Manufacturer

Sean34 - the Sony DVP-S7700 or the Pioneer DV-47A (needs Superclock3).

A good DAC will buffer the data stream it is receiving so that the timing from the transport is irrelevant. So the timing will be based on the clock in the DAC, and the assumption that the DAC knows the rate to play the data back at (which, in most cases, is present on the front panel of the DAC as an indicator light or timing readout...e.g. 44K, 48K, etc.).

The only room for error is the transmission of the data stream, which needs to move data at a fraction of the rate that computers routinely send (and receive) digital data (losslessly, I might add, over extremely inexpensive cables).

Steve N - I appreciate your perspective, but I'm guessing that you don't have your DAC, personal computer, and house fan all plugged in to the same power strip. My only point being that when evaluating audio components that are bad about creating electrical hash on the line (Transports), audible differences may be partly due to power quality differences seen by the rest of your system.