Maybe just my purist preferences playing around here, but I don't think that flat necessarily sounds soulless like that, although definitely a bit boring. For me, flat means tight bass in quite meagre doses, unexciting but natural mids, and a somewhat cold but not harsh treble.

To be fair, I don't like DF either, because I don't think DF is neutral for mastered tracks, maybe for recorded tracks at most. For mastered stuff, something like IEF neutral is closer to flat for me.