different voices in polyphonic instruments

im composing a oud concerto and with respect to dynamics there's seems to be a problem with different dynamics in different voices (1st 2nd 3rd etc...), the problem is that to a given score during a given time there's only one possible dynamic completly disregarding different dynamics in different voices. i know that for that to be possible i would have to have N midis for N voices.... but thats to much work when im simply trying to listen to what im wrinting.