iTunes 9 Bit Perfect Output?


Has anyone here done a serious sound quality comparison between iTunes 9 and other players with a (preferably Asynchronous) USB DAC? This question applies to Windows Vista and Windows 7 systems only.

My understanding is that iTunes was generally incapable of bit-perfect output to an external DAC, however, starting with iTunes 9, there is an option for WASAPI output available in the quicktime control panel that should generate a bit perfect signal. However, in my Windows 7 64 bit system, this option is not available (greyed out). I am wondering if it is just broken or not compatible with Windows 7 or 64 bit OS? The setting I am talking about is in quicktime-->options-->quicktime options.

Anyone have any thoughts on this?
blackstonejd