if the ONLY aspect you'll use a DAC for is pc/mac audio out, quite a few DACs will be at a premium... as the balance of the DACs versatility will be truncated severely by that approach... unless you're considering a budget approach.
The apogee mention is a good one. I own the Bel Canto DAC 3. Initially, I felt pc music through it was great! actually I still do, but I've not stopped looking for another option or path.
The BC DAC 3 does afford one more than just usb audio. It is limited too by it's 16/44.1K input via USB.
With other imputs, it can handle up to 24/96 PCM data. What I've heard recently by way of upsampled music from the 16/44 to 24/96, and 24/192 is showing itself as becoming more rounded, smoother, and with more dimensionality, as the rates go up. IMO.
AS I do take advantage of the flexibility of the DAC3's inputs, it's a good enough value for me, for now. A very fine performer all around.... but used just for PC/Mac audio? I wouldn't say it is.
So do think about current AND future needs too while you ponder which way to go, or what to get, and of course, your systems needs too. Good luck.