I need to maximise the output volume when exporting mp3 files, so the backing files I create are loud enough when a choir sings with them…
This isn’t an direct answer, but I always export as WAV and drag into Audacity (a free, simple audio editor).
It’s really easy in Audacity to Select All and amplify a bit. Audacity even includes automatic clipping detection so you don’t bump it up too much.
Another option is to open the mixer, scroll to the Output channel and show the Inserts panel. You can then add the Maximizer plugin and tweak the settings there to get something that sounds louder.
Thanks to you both…
Building on Paul’s comments, while you are in the inserts area, you might experiment with some other effects. In other words, it may not be simply that you need more loudness. You may need more “detail” in the track. If you are playing the track for the choir using stereo speakers, make sure to pan the various instruments using the mixer.
And a little compression can go a long way to making the inner parts more audible. I suppose the maximizer will do this on a gross level, but you might want to insert a proper compressor earlier in the insert chain. Perhaps even a multi-band compressor. I am not at my Dorico computer at the moment, so I can’t recall what effects are available in the standard installation. If you are doing a lot of this, you may want to invest in some third party mastering plug-ins.