to further clarify the 3 IEM's I mentioned:
FXD80 - heaviest bass of the 3, warmest midrange, crisp treble, 2nd most amount of detail, 2nd best sound stage.
N-ergy - 2nd heaviest bass, more forward midrange that is on the bright side, treble is very good especially for cymbals, least amount of detail but is very close to the FXD80, best sound stage.
Etymotic HF3 - least amount of bass but probably the best bass punch, more forward midrange that is on the bright side, treble is very good with the most amount of detail, I find the treble a bit to crisp for cymbals on some recordings. Soundstage is the smallest but due to the detail of the IEM instruments never feel crowded.
Could you compare the FXD80 to the FXT90s?
Do the 90s have a little less bass? May be a more forward mids as well?