NAS connected digital streamer with digital out?

The Squeezebox line of products does this. Connects to NAS via ethernet or wireless (wired ethernet preferred, especially if streaming high-res). Offers both coax and TOSlink digital outputs.

The Pro-Ject Stream Box DS has digital and analog outputs. It's also very convenient for listening to Internet radio. It looks and sounds good, is a convenient size and is reasonably priced.

The Linn Majik DS and Linn Sneaky Music DS also have digital outputs in addition to their analogue outputs. These are more expensive than the Pro-Ject unit, and the Sneaky Music DS includes built-in stereo amplifier.

All in all these are units that sound great at three different price points and in three different form factors. I hope that one works for you.

What are you trying to play? Ripped CDs or high def files? The reason that I am asking is that there are two streaming players in the lower price range that come to mind. The first being the Squeezebox touch and the other being a Sonos.

The advantages of the Squeezebox are that it is capable of playing hi rez files and can be controlled via infrared remote, in addition to other wireless methods (iPad, iPod, etc.). The downside to the Squeezebox is that it can be tempermental. I've had to reset mine three times in the last week. For some inexplicable reason, it has quit playing my files downloaded from iTunes and it doesn't want to let me onto MOG. Setting it up to work with an NAS is also a bit more involved.

The Sonos won't play any files over 16 bit with a sampling rate greater than 48khz, but other than that it is rock solid. I've never had to reset mine and the software is also very refined. Another downside to the Sonos is that it cannot be controlled via infrared remote. All control is via a computer app or an app for iPad, iTouch or some other gadget over wireless. The setup for pulling files off of an NAS is also so easy that even a caveman can do it.

If you don't need the hi rez capabilities, I'd go for the Sonos. It's bullet proof and has caused me far fewer headaches than the Squeezebox has. With music ripped from CDs, I can't tell the difference between the units.