They have some superficial resemblence in overall specral balance but are totally different in presentation, really the very opposites of each other-1R is much more direct sounding, emits much better weight and body to the notes and has a more focused imaging. MA900 is much lighter (in tonal weight) and spreads the soundscape to a perciveable wider area and further away, though not as far as say AKG K701. It has a more diffused sound than 1R. They both have a lower-mid emphasis but 1R's more forward and has a greater upper-mid dip, MA900 has more smoothness in it's midrange but has some bloom in the mid-bass that takes away some clarity in the trantition to the mids. Bass-wise i think the MA900 has a fuller, more even response but packs less punch and is a bit looser, 1R defintely has a tighter kick. They're both colored but MA900 has the more accurate tone than 1R's, though i find the latter more dynamic, if somewhat darker.
At least that's how i hear it.