Technical Information on Replay Gain Adjustment

Here's a summary of the process:

For Each File:

1. Figure out how much we could safely turn a file up using the peak level.
2. Use (1) to see how much we could safely add to the replay gain level

Auto preamp will be the minimum (2) from all the files.

Example with 2 files

A: peak level: 50%, replay gain: -10 dB
B: peak level: 75%, replay gain: -4 dB

A(1) = 50% -> +6dB could be added safely
A(2) = +6dB - -10dB = 16 dB could be added to RG

B(1) = 75% -> +3dB could be added safely
B(2) = +3dB - -4dB = 7 dB could be added to RG

Auto preamp = min(A(2), B(2)) = +7 dB

During playback:

Actual gain (A) = -10 dB + 7 dB = -3 dB
Actual gain (B) = -4 dB + 7 dB = +3 dB