Using Nec 2500 too burn DVDs, I find the audio is lower on backup disc than the original. No great hardship to turn up volume, but is this normal...Thanks

Are you removing extra audio tracks when making your backup?

If you are keeping 6ch audio (5.1 DD) and playing it back on a non 5.1 DD setup, the volume will be lower, than if you choose 2 ch audio.

The audio should be completely unchanged from the original, but then again you never said exactly what process you were using to create the backup.