I would heartily recomend the Oppo Sonica DAC, I use one from my main Computer / DAW to my Head Amp from USB when mastering CD's and can say I have only good things to say about it. I don't use anything else on it but the USB straight in to the Head amp. It does have the apps for networking and it has a superb volume control which again I don't use but it could save the cost of a preamp and with less electronics in the mix should be more transparent. The DAC chips inside are Sabres and the top ones and they are very well implimented so they give top notch sound but do take a long time to burn in. If you can afford to put the digital output from say a DAB radio trough it for a couple of weeks before you do some really serious listening it will reward you in the end with a really open sound for the money.
Good luck, Jim.
Good luck, Jim.