I agree with you, there should be something that easy. The good news is that there is! It is called Laticrete 125 Sound and Crack Adhesive. It works as a setting adhesive, crack isolation treatment, and sound barrier all in one. Here is the link for more info:
www.laticrete.com/Archit...
Michael Prachniak - Expert Tile and Stone Consultant and Writer, Owner - Tile Productions
Check out FAF''s tile section!
www.findanyfloor.com/tile/TileFloo...