Reply to Remastering Mashups and Edits?

Hey Guys,

I have produced some Mashups and Re-Edits in my DAW, by simply dropping some acapellas over (popular) instrumentals and adding some Effects. Nothing special really. The acapellas and especially the instrumentals have both already been professionally mastered before (as i bought them directly from Beatport & Co.).

Do i now have to remaster my edit all the way over or is it ok, to simply apply some leveling of gain controls within my DAW, in order to play them at my gigs? What do believe is the better approach? How do you guys do this?