With regard to the iDSD BL with Aeon (I cant speak to Aeon but I did use it wiht my Ether C 1.1).
The iDSD was a fantastic pairing as I found it added a bit more body to the sound. It also had the advantage of having bass boost which is rare on higher end devices, Not that many would consider the iDSD Black High end, but it certainly keeps some high end setups honest.
I also used the Mojo. The mojo to me sounded "better" with the Ether. It really portrayed the mids in a special way.
HOWEVER I overall preferred the iDSD for its low end and body.
Having a good quality bass boost was fantastic and to me made the Ethers more flexible as I listen to vastly different genres.
The iDSD also portrayed a wider and airier presentation with the Mojo sounding more intimate.
Both are fantastic, I just preferred the diversity of the iDSD, given how revealing the Mr Speakers cans are, any changes upstream really flowed in all their glory through the cans.
I am currently debating getting a pair of Aeons or ZMF Ori. Very different cans, but my preference naturally is for the Ori sound. However it is hard to pass up the clarity and refinement of the Aeon. I would however also need to purchase a new iDSD BL