I've compared the Ack! dAck! 2.0 versus the Audio Mirror D1 in my system, and I think Skyboy's second post in the link Dave pointed you towards sums it up well.
Briefly I think the Audio Mirror is a more dynamic, expansive and organically colored DAC compare to the Ack! which has a more neutral, laid back and even balanced presentation.
Briefly I think the Audio Mirror is a more dynamic, expansive and organically colored DAC compare to the Ack! which has a more neutral, laid back and even balanced presentation.