I wouldn't want any software altering the dynamics of my music files. Maybe some compression applied to the output would be okay. - so I prefer Musicmatch's approach. Compression changes the perceived volume or average output volume, but not the max output. So, I would have to think that it is not false advertisement.

What is true advertising? Making tracks the same volume level or making them "seem" the same volume?

Isn't it true that not all tracks are normalized to 0db?