On the PC, you also need to achieve the correct gain and remove your practically unused headroom:
To do this, you need to edit your already recorded files and normalize their levels so that their peaks not exceed the maximum possible level, if possible.
For future recordings, you need to ensure that a higher level is present at the desired recording output during live operation.
Your inputs/outputs may not yet be correctly leveled.
You may be able to reduce the input of your PA to achieve a higher level at the LR output.
You may be able to use another stereo mix specifically for the recording and increase all levels there accordingly.
You can also find relevant information at the end of the article linked by Keith.