The AE uses mini-optical. My unit came with an optical cable and an adapter. I kept the adapter and use it on a VH Optocoupler. Keep in mind that the AE only has an optical jack so if your DAC does not have an optical input, you will need to get the AE modified or use a converter -- I use the Monarchy Upsampler which converts the signal to coax.
I am just getting started on comparing the AE signal to my RA Opus 21. So far the differences are evasive. As you might expect, there are huge differences between file formats with Lossless being head and shoulders above the others.
FYI Keyspan has a new remote control integrated with the AE and iTunes. A bargain at $40 on Amazon.