Best DAC for CD redbook playback from a PS Audio Perfectwave transport


I just purchased a PS Audio PWT and will use it to listen to redbook CDs. I've read that the best playback is with an I2S hdmi cable. So, a suitable dac would be one with an I2S input, such as either a Wyred4Sound dac or a PS Audio PWD. But, if it's just for redbook CD playback, can I suffice with an older MK1 version or do the updated versions (which I presume are primarily geared toward improving computer based systems) also significantly improve CD SQ? Again, it's just for CD playback.
tweaknkeep
Thanks stereo5. Yes, I've read that I2S is the best. But, considering it's only for CD redbook, is it worth splashing out on the latest version dac with and I2S input (even a PS Audio Directstream), or is it wasted money? (e.g. just buy an older version used)
For what it's worth, I'm so happy with my PWD II that I have no yearning for a Directstream.  I'm using the Bridge II with fantastic sonic results, but the Perfectwave Transport hooked up by I2S should be just as good.