Export in SE3- Eq Changes

First time posting so thanks for any help. I have been having trouble with the exports on my projects using Cubase SE3 - a noticeable bass boost occurs at certain frequencies that either messes up the export a bit or just boosts the bass, depending on where the frequencies lie in the mix. Either way, I’m not getting the mix that I’ve spent so much time mixing, but instead some odd rendering.

To make sure it wasn’t perception or different wav file players, I exported a mix and re-imported it into Cubase on a stereo track and a/b 'ed it with the original, adjusting for volumes and such. It was very clear that there was a bass boost occurring in the export. Is this normal? Is there a way to fix it or settings that I should be setting differently? Do newer versions of Cubase have the same problem? I have also tried exporting to a hard disc recorder via SPDIF.

Again - thanks for any help.