Nicks25,
I tried 2 different dac’s into my 2170 in the beginning and I got much better results using the digital inputs on the 2170,as others have stated.
I use usb input from a Sotm ultra renderer that’s hooked up via Ethernet in my local network.To me That’s one of the many pluses of using a 2170 or 3400 is not needing or wanting any other Preamp,Amp,or dac.
I’ve recently been able to borrow a couple of top music servers,Lumin U1 and Aurrender W20 to compare to my highly tweaked computer running server 2016,Roon server,Audiophile optimizer,Fidelizer,and most importantly HQ player,the results were even though both of these servers are quite nice and very easy to use neither one beat the sound I’m already getting from my computer especially with all the tweaks in upsampling and filtering that HQ player have.
If you have more questions give me call sometime,
Kenny.