Processor DACs

I am shopping for a new Processor. I’ll probably get an Integra DHC 80.3, so I am curious if anyone has ever compared the onboard DAC of their processor to an established benchmark DAC such as a W4S DAC-2. Since my music server has USB outs, it would require purchasing a USB to S/PDIF converter (such as the Anedio U2) to hook up the processor to the server. Before spending the money on a converter, I am wondering if people have tried this out, and what their experience with it is. It seems that most mainstream processors have solid DACs to do all the Dolby Digital conversion, so wouldn’t it make sense that they should perform excellent as a standalone DAC? I would appreciate your thoughts and experience.