May be most of peoples know but:
Is it relatively simple possibility to change music volume of several FLAC files except volume of amplifier or dB botton in fb2k ?
You could ReplayGain scan them. Or you can simulate a ReplayGain adjustment by manually editing the ReplayGain tags. There is an editor in the hidden options, which you can either enable by default in Preferences, or you can hold the shift key when right clicking on the tracks to display all hidden items.
OK, its clear now.
(BTW it is possibility or custom to show as answer/solution of my question in fb2k Forum? if yes how?)
I don't think this forum script supports that, but it does have a search feature. Maybe someone should collect these in a Frequently Asked Questions pinned topic?
I feel like a wiki would be more suitable for that kind of content. Of course then it would need pointers in the forums towards it. But stuff like titleformatting is already there: