All songs need to be analyzed in MC otherwise replay gain does not work.
Not quite. More accurately..otherwise soundcheck when enabled on iPod will not work on the unanalyzed files.
In general using Replay Gain the overall volume goes down.
Proabably.
> In MC this can be corrected by adding a fixed or playlist dependent Db amount.
If you are talking about using the right click 'Volume Adjustment' option to do this, the answer is no because in my testing I found that the volume adjustment was ignored on iPod when the soundcheck feature was enabled.
This correction does not affect the volume on the iPod
The 'Volume Adjustment' change definitely affects the volume on iPod but only if soundcheck is disabled.
> Soundcheck (on the iPod) only works with analyzed songs.
Yes.
> Soundcheck makes all songs play at the same volume.
It depends. If the tracks are analyzed in MC and have a replay gain setting, that setting is transferred to iPod and if Soundcheck is enabled, then the replay gain will be applied so files will play at the same volume.
> The Volume Adjustment does not work in combination with Soundcheck switched on.
Correct to the best of my knowledge at this point. I will continue to verify this.
How can I use Replay Gain settings and adjust the overall volume on the iPod?
These two appear to be mutually exclusive. I will test more.