Arcam rPAC ... opinions?

Have you tried this little device and what do you think of it. Does it drain your laptop's battery ?
I haven't tried the rPAC, but I have a Centrance Dacport, which is a similar device. I haven't noticed any drain on my laptop battery, and it makes a huge difference in the sound quality. In fact, I used it as a DAC preamp combo for my full sized office system for a long time and it sounded really good.