@geek101
Aeon Closed have a flat impedance of ~12 ohms, so it's really important your headphone amp has 1 ohm output impedance or less.
Both ADI-2 and Atom do, so both tick that important box.
One cool feature ADI-2 has is Bauer crossfeed DSP, built-in:
http://bs2b.sourceforge.net/
I really like Bauer crossfeed DSP with headphones and it's cool that ADI-2 has it built-in, for any input.
I've considered the same combo you have but built-in Bauer crossfeed DSP is enough to make me go with RME.
ADI-2 has other DSP options built-in also. It's quite feature packed.