i'm not unsatisfied with the output from my realtek hd, but there seems to be quite a bit of noise and interference, i'm hoping a dac will clear that up, as a plus, i can use it with my laptop to (which actually has pretty decent sound output)
and shin, everyone is recommending a dual AD744 setup, those are analog devices opamps, and i'm trying to find a source that A) doesnt charge way more than they're worth/cost and B) will sell in quantities less than 100.
you'll need 2 of those, and a dual opamp adapter with 2 dip8 sockets... so you're basically cramming 2 opamps into a single socket.
you can always start with the stock setup and see how you like the sound, a lot of equipment solders them in so you have no freedom to roll (aka, change) them, but the AUNE gives you the option of changing them, but by all means you dont have to.
this is what you'll have....
and this is stock (look near top right, you'll see a single stock opamp, vs the dual ad744 above)
make more sense now? there are a few other circuits you can upgrade easily, but that is said to have the most impact, after that the next logical upgrade would be a cleaner power source.