Now that I use the Cayin, I almost always use two devices when I'm traveling (even short distances), and I never thought that would happen. With the Hiby app, I can control the Cayin from my phone. It's very nice to be able to keep my DAP in the pocket without dealing with the headphone wires on my phone. Even with the Mojo banded to the Cayin, it's a manageable coat-pocket rig (although I lose volume control). I don't bother with the Mojo if I'm using anything other than CIEMs or the HD6xx.
Given that, and that the Monolith is nearly the equal (measurement-wise) of the Mojo, I'm hoping for it to provide a DSP solution to the 'in-your-head' sound of near-field transducers. I know it's possible, both Smyth and JVC have convincing versions, and the Smyth in particular has been reviewed by people whose opinions I trust and they say the sound is a game-changer. Knowing that, it should not be difficult to create a canned HTRF via DSP, and that is what the marketing of the Sensaround tech seems to indicate. I'd actually give up a bit of inaudible distortion to get a more expanded sense of listening space with headphones.