You guys are missing the point. Let me try again. When using the DAC's USB input jitter is dependent on the module. When using the DAC's SPDIF input jitter is dependent on the transport. Good transports have good jitter numbers. Pro tip... most transports are terrible compared to stock USB modules. A good CD transport is generally $1500+. Quite a few stand alone usb>spdif converter are however quite good and much less. Metrum, Audio-GD, W4S and PS all have great stock USB modules.
Quite right. I re-read your post and realised that I had missed your point entirely.
A lot of the older transports probably are pointless with the newer USB modules. The speed at which DACs seem to be progressing will probably render all the current transports useless within a couple of years.