MMM's won't match HD650 in highs. Not ever. The > 20 dB difference in highest end (beyond 14 kHz) is huge and impossible to correct without introducing major distortion.
It also seems that they have more resonance by looking at the step responses. And these do provide plenty subbass, but in both cases the decay is subpar. So you end up with "headphone" bass.
Who knows, maybe a simple mod fixes that?