Some All -> Audio setting clarifications

[2mg]

Hi,

under All -> Audio options, there are:

- Audio Gain
- Replay Gain mode
- Replay Preamp
- Default Replay Gain

My questions are:

1. Is Audio Gain just a preamp for any audio, eg. just raises default volume? Or is it something else?
2. Is Replay Gain mode tied with Replay Preamp in such way that it also need's audio files to have replay gain information?
3. Does Default Replay Gain really work on audio files without gain information, and if yes, would it be better a better to "smoothen" audio lows/highs than pure Normalization?