IMO, it's not easy to compare outboard DAC to internal DAC inside the receiver.
Internal DAC has the benefit of having direct connection to preamp/amp stage without going through additional connector/cables. A secondary benefit with today's surround receiver is build in room correction and sub woofer cross over support in the digital domain.
External DAC is usually used in much higher quality separates system that already had better preamp/amp stage.
Connect an external DAC into the receiver will be a good comparison, but that is rarely done since most people who purchse surround receiver will not buy an external DAC. And the analog input stage of a receiver is not likely to on par with separates.
Basically I would suggest that you need to spend tons of money to get some sonic beneft from external DAC and it usually involve getting something more than a typical surround receiver.
Internal DAC has the benefit of having direct connection to preamp/amp stage without going through additional connector/cables. A secondary benefit with today's surround receiver is build in room correction and sub woofer cross over support in the digital domain.
External DAC is usually used in much higher quality separates system that already had better preamp/amp stage.
Connect an external DAC into the receiver will be a good comparison, but that is rarely done since most people who purchse surround receiver will not buy an external DAC. And the analog input stage of a receiver is not likely to on par with separates.
Basically I would suggest that you need to spend tons of money to get some sonic beneft from external DAC and it usually involve getting something more than a typical surround receiver.