I have the Xonar DG soundcard which obviously has a built-in DAC. If I buy an external DAC that is not a USB DAC, will that be using the Xonars DAC and the new external DAC?
Wouldnt the Xonar's DAC have already processed the audio?
To achieve double-dac-ing, you will need to have a ADC (Analog to Digital Converter) in between.
Well, the DG has a toslink digital out, which can be used to connect to external dac, and doing so will bypass the built-in dac section on DG.
If you connect an external DAC to the Xonar DG, using S/PDIF optical, then the Xonar DG's DAC will be bypassed.