I don't own a PHA-2 but isn't it running on asynchronous USB mode and should be mostly jitter-free?
Anyway, Dragonfly is an USB DAC that only output analog signal. It doesn't do USB output and therefore there is no jitter reduction to speak for. You seem to be worrying about an non-existing problem.
Ahh. that's right! I forgot that the Dragonfly was 3.5mm out. OK. Thanks.