You should read this thread: http://www.head-fi.org/t/211770/w5000-owners-amp-registry
Other amps I've read about, but not heard for myself, that you might want to include in your research: Yamamoto HA-02 and Trafomatic Experience Head One.
I'm not very well-experienced in budget DACs, but if I had to recommend anything to look into, they'd be: HeadAmp Pico (if you need just a USB input), Arcam rDac, or Schiit Bifrost (not out yet, but soon). The absolute cheapest options I'd recommend would be the DIY-based AMB y1 or y2 (Gamma1 / 2, more at www.amb.org/audio) or possibly studio-gear type DACs made by companies like E-MU, PreSonus, etc.
Edited by Asr - 9/17/11 at 11:30pm