Having your computer hooked to your audio system (whether thru a DAC or any other route) is a big chance for noise from the computer to infiltrate your audio system. Some of the obvious paths are digital interconnects can be EMI receivers and/or transmitters, computers have switching power supplies that add all sort of noise to the mains (in addition to the computer power cord itself being a receiver/transmitter of EMI generated by the big current spikes from the computer’s power supply), groudloops, having more routes to ground in the system adds more groundloops which are receivers and transmitters of EMI.
Jitter is one path for noise to creep into an audio system thru the DAC, but just having a DAC, even a “perfect DAC”, will still involve making more groundloops (digital interconnects, analog interconnects, power cord.)
Unlike most audio gear designers a computer design only cares about EMI enough to meet the FCC, etc. restrictions which are much too high for most audio systems.
Tho I standby my claims about the jitter rejection of the DS and am reasonably proud of that work, it’s too easy to forget about all kinds of other interference having anything digital in a system can cause. The DS is a good citizen with EMI radiation, but it’s obvious that work remains to be done noise rejection for, say USB, etc.