NAD headphone jacks are of good quality, probably comparable to the cheaper $100-$200 headphone jacks but not in the league of the PPA.
The NAD 1300 is a preamp, so you still need to buy a power amp to run speakers....

Candyman's suggestion of connecting your sound card directly to a power amp is a good one, I use an Adcom amp with my Audigy 2zs and it works fine, I just use my software volume control to adjust volume. This saves you from buying a preamp. But power amps usually don't have headphone jacks, so if you want one, you'll need a preamp. Or just get an integrated amp/receiver.