OP,
The DAC in your PC is located in a very noisy, vibration ridden environment and is not purpose built for high quality sound. Just being able to play high Rez files doesn’t mean they sound optimal. You might have a look at my system… every one of the 9 components weighs at least 35 pounds and performs a specific function. The more design effort, isolation, high quality components used, the better the sound. There is almost no end to this.
External DACs are available from a few dollars to well in excess of $20,000… I have owned and listened to at least a couple dozen from $100 to $22K. In general, the more expensive the better they sound… exactly like other components… streamers, preamps, amps, speakers and turntables.
The optimal sound will be from a system is to have similar and complementary components. If you want to do a single purchase and no more… then think of a USB or general purpose external DAC costing somewhere in the vicinity of your receiver.
Just running your analog output through your receiver may sound better… probably… but so many variables try it.