I've been using the Pico Amp/DAC (purchased used) in my office for the last few months as a DAC and also as a portable solution when I travel.  It never ceases to amaze me just how well it does in both roles and just how flexible it is in general.  It sounds great and I can't think of another piece of gear that I own or have owned that represents better value for the $$.  It also says something that I, a tried and true DIYer, simply stopped trying to build something as good after several failed attempts.