I have the XDA-1 and it was fine with my AudioEngine 2's on my desktop system. However, when I upgraded the speakers to the KEF LS50's the XDA-1 became a massive weak link. So now it resides unplugged in my closet replaced with the fantastic Benchmark DAC2. Before I bought the DAC2 I moved my now replaced DAC1 from the main rig to the desktop KEF system and it also was not very good with the KEF's. The DAC2 is incredibly good.
So the lesson I learned from this was that the quality of the speakers dictates the quality of DAC needed.
So the lesson I learned from this was that the quality of the speakers dictates the quality of DAC needed.