[sagrath]

Thanks @scott967 .

But I still don´t understand how I must proceed to make my music plays always on same volume.

An exemple is: I have a Fire Inc. artist. And his two songs has a too low volume compared to Trail of Tears artist (this one has a nice volume level).
I Just Want to put my Fire Inc. songs (and others) in the same level of my Trail Of Tears songs. I don´t know how much is the db level of Trail of Tears, but is cleared that is more than Fire Inc.

I´ve try to put both option in music setting (files without information of replay gain level and files with information replay gain level) in 100db, but the level stills different.

Thanks for your help anyway.

Edit: I did it! 
I was using wrong option in foobar2000. 
This time I select ALL my songs, and use the option "Scan Selection as Albuns (by tags)".
As I don´t have so much songs (it´s about 3k) they took 15 minutes to scan all songs and 10 minutes to update tags
Now in kodi all songs have the same volume. And the option "files with information replay gain level" is 89db.

Thanks to all!