Hi,
I have heard the NuForce HDP and the Schiit Bifrost. The HDP is very clear, as is the Bifrost. Both are not really warm or, as some people like to say, "musical." They have an analytic approach to the music. The Bifrost seemed to be a bit more aggressive and dynamic when resolving some of the fast transients in electronic music. The HDP is no slouch, though. They are both near the same level to my ears, so pick the one that has the functions you desire and the size that you desire. Some would like a nice little HDP so they can have nice sound wherever they are, and some would prefer the Schiit for a solid rig at home. I like the look of the Bifrost a bit more, though. :P
Hell, if possible, try to hear both. Maybe you can hear more differences than me and your ears may like something different! :D
Cheers and good luck with your decision,
Dan