Poor sound on export

I suspect you are right that your problem is not related.

Why do you think you are experiencing a loss of volume? Do you want to record a 10-second sample then post the .WAV and .MP3 files? Before you export take a snapshot: Tools > Screenshot > Capture Full Window.

Edited: Please disregard. I see you have posted this issue in a different thread here How to make Audacity playback sound volume equal to sound volume of WAV/MP3 file when exporting?
where you have already received some replies.