Last night, I had a strange problem. I had Replay Gain enabled with 'Automatic based on current playlist' set as the adjustment.
I played from a list that included all the audio in my library. The volume was really quiet.
It turns out this was because I have a recording of a rain storm that has a +17 dB Replay Gain.
This means the 'Automatic based on current playlist' wants to turn everything down 17 dB (14 dB actually, since the peak level of 70% allows 3 dB of headroom before clipping).
So a Metallica song with a Replay Gain of -20 dB becomes -37 dB when rain happens to be in the playlist.
The volume levels between the rain and Metallica are the same, but the extreme attenuation required to achieve this isn't what I wanted. I wasn't listening to the rain, it just happened to be in the playlist.
I wonder if it would be better for 'Automatic based on current playlist' to have some cap, and allow really quiet tracks to play quieter than other tracks. The cap could be an absolute decibel threshold (say +3 dB or some percentile so 5% of tracks would play quieter than others).
Thoughts?