Keep in mind, I'm of the mindset that transports are overrated. The DAC is where it's at. Furthermore, I'm conservative on the degree to which jitter matters, so I'm inclined to think that you're going to have a great setup with your favorite DAC coupled with a music server.
But given that...
Which of the following are you using now:
1) separate transport and DAC with a standard S/PDIF or AES/EBU connection
2) separate transport and DAC with a master clock generated by the DAC;
3) a single-box unit.
If it's 1, then a music server shouldn't be any worse than what you have now. Just substitute it for your current transport and you're good to go. The Transporter discussed below might be overkill unless you're sensitive to jitter, in which case its careful clock design might provide some benefit.
If it's 2, then with you can keep this architecture and all its jitter-reducing benefits by using a network music player with a master clock input. The SlimDevices Transporter qualifies, for example. (See the "High-end network music player" thread.) You can drive the Transporter using your DAC's master clock, and your DAC should be none the wiser. You'll be leaving some pricey analog electronics unused in this case (i.e., the Transporter DACs) but if you already like the sound you have...
If it's 3, then you have a couple of choices. First, you can use the Transporter's built-in DACs. It was designed with the audiophile in mind, and the owners on the aforementioned thread are happy with it. Of course, they were believers in the network music player concept beforehand, so they might be biased, but they're also audiophiles. Audition if you can.
Or, you can buy a new DAC and music server and put them together yourself. A master clock arrangement alleviates any objectivist limitations of this approach; but honestly a good buffering DAC should do great.