So I basically use Vegas Movie Studio 13 to make animations, meaning I use .png files to make my videos. It looks like/It has the same colors my .png files in the preview, but once I render it, it turns more saturated/contrasted. I can't seem to find anything that works.
It's your player which is set up, as most are, to play Studio RGB levels stretched out to full range. This gives increased contrast if your export is full range. Best to follow Musicvid's advice.