I'm looking for a dac to pair with my laptop and Sennheiser HD 598 and Audio-Technica ATH-A900X. I'm between DacMagic XS and Microstreamer (both cost about 190 dollars in the US). Which one would you pick?

I'm looking for a portable player with support for FLAC and given that I have only $300, it seems that Cowon X7, X9 and C2 are the ones I can afford (if there are others please let me know). How would you compare them? Is there a clear choice among such models?

How can I make sure that Foobar's attenuator is not being used? (i.e. I want to disable it, so that I can control volume only from the system, which is tied to the DAC in the analog domain).