Had a chance to audition the D3 vs Dragonfly. D3 seem to be better in bass (more) but felt thinner in the mids. Dragonfly is reverse. D3 runs a bit warm while Dragonfly stays super cool. Hard to decide.
MassDropFanD3 has higher output, and to me, overall less "harsh" sound signature. Both are good, biggest advantage of the Dragonfly is that it can be ran off the iphone SE (or I presume Android Smarphone) via apple cam 3 adapter or similar mini usb adapter for android. D3 needs separate power source when attached to some smartphones; Iphone SE can't power it. If only for the sound, I would go for the D3, but you are best served if testing by yourself.