I used the dac 2 against the benchmark dac1 usb and the dac 2 is better in every way. The bass is clearer and the highs are more natural. The overall presentation was just easier to listen to.
But now I have upgraded to the invicta dac and again another level up. But with that said the dac 2 price to performance is extremely good.
Best upgrade for the dac 2 would be a very good usb to spdif converter. I used the audiophilleo 2 with pure power.