I am on the verge of buying a Cambridge Audio DACMagic DAC. One of the things CA claims is that optical audio from computers (like Macs) is not metronomically syncronous -- i.e. that some bits are delivered out of order, yielding unwanted overtones. With AirPlay or AirTunes, is there such jitter present? Will a good DAC sort this problem out? Will there be a noticeable sound improvement? My signal is ultimately being played through B&W 685s. I have to say that, at the moment, I think the sound has room for improvement that has little to do with my my speakers. Current setup is AirTunes playing ALAC > integrated amp > 685s.