bflat
Headphoneus Supremus
This sounds more like a sound signature preference thing. Technically those DACs are equally competent and the DP-X1 outputs more than enough power, but it doesn't sound like the signatures match as well for your tastes as compared with the other gear you have used, but that is a personal thing. Bigger cases and components by themselves are meaningless, if we implemented and tuned the same DAC chips in a small DAP case size or a desktop DAC the sound would be transparent to the user so desktop versus portable doesn't have to mean anything at all sound wise. They can differ, but it isn't guaranteed simply based on form factor of the components.
Sure it's all subjective. Where do you get the impression that I state the bigger form factors sound better than smaller? Both Mojo and Vorzuge are smaller than X1 and ALO is nearly the same size. It's a bit of apples to oranges comparison, but I find no correlation to size of device and sound quality. If I knew of a DAP that would give me the same sound quality that suits me on Laylas, I would buy it because I don't particularly enjoy stacking portable devices.