I was just wondering about this one day, so I thought I'll discuss it here..

To overcome my low'max volume' on my MP3 player, I use MP3 gain to apply a track gain of 99.0 to all files. Most of the times, the tracks clip.

I have had no difference in hearing those tracks, despite the clipping.

My questions:

1. Is clipping really noticeable on majority of the tracks?
2. If I un-do the gain to the track's previous value, will it 'un-clip' to the previous state? Sounds yucky but that the best I can put it in.

The distortion caused by clipping will sometimes be masked by the signal and sometimes not. If it's noticable for *you* depends on how bad the clipping is and on how sensitive (trained) you are to hear clipping. In your case I'd try to do some ABX tests:
mp3 decoded at non clipping level
vs.
mp3 decoded at louder level (clipping), amplified afterwards to matching volume.

I'd use a wave editor to find positions with most clipping.


Yes.