It's a problem that arises for a lot of people, and there's actually a fairly straightforward explanation for it.

So long as you're using an ASIO driver in your DAW, either as a software driver or via an audio interface, if you drag the rendered track back into the DAW and play it, it should sound the same as before you exported it. I'ts because your on-board sound driver included in the computer's motherboard will often be taking over from the ASIO drivers when playing tracks back in iTunes/VLC/media players, and these drivers (especially RealTek High Definition Audio ones) will colour the sound with their own broad EQ settings.

To quickly check, right-click the volume control in the notifications tray and hit Playback Devices. Right-click the current sound device and hit Properties. Check the Enhancements tab, and un-check every option there. It'll be stuff like Room Correction, Low Frequency Adjustments, Dynamic Equalisation, etc. Once it's all unchecked, play the track again. It should be much closer to what came out of your DAW.

To wrap it up, what you're hearing in the DAW pre-render is what you should end up with in the end. If you haven't, chances are, its the PC's own audio drivers causing havoc.