I installed mp3gain and looking at the manual it seems it is not possible to write replaygain tags while using album tags. BUT perhaps I missed something.
according to the manual:
mp3gain optionally writes gain adjustments directly into the encoded data. In this case, the adjustment works with all mp3 players, i.e. no support for a special tag is required. This mode is activated by any of the options -r, -a, -g, or -l.
If none of the above options are given, the recommended gain change is instead written to a special tag in the mp3 file. In this case, the adjustment only works with mp3 players that support this tag. Some mp3 players refer to this as ReplayGain. The tag is written either in APEv2 format (default) or in ID3v2 format (with -s i). If you only want to print the recommended gain change (and not modify the file at all) you may use the -s s (skip tag) option.
Can you please help? Thanks