Quote: Fx101 has a bigger boomier bass, sound is thicker with better highs (not the best). FX40 has a more refined sound with better bass (little less than the Fx101), they are "treble heavy", so watch out. Better build quality, both better than the FX8. but i would recomend the 3580 for cheap good all-arounders. a little less bass than the Fx101 but overall, its a better soundin iem Also check the Sony MH1C thread.