Wrongo Hano, mass will do little for containing low frequency propagation (I could have found a better word, but what the hell, I like the sound of it, and it sort of fits...
). Concrete is a horrible low frequency filter, as most any material is.
Dead space is your friend. The more the merrier.
If your ceilings allow, you can try this.
A floating floor. There is a company that makes these rubber blocks just for this very thing. You then build a floor atop of these blocks that sit on the original floor. This will help two things in particular.
1- Remove a wood to wood contact between the floors. Rubber is a very decent insulator for sound waves.
2- Will create an air space below your new floor. Sound hits the new floor, goes through it, hits air space, hits another floor. Little will get through the next floor. Of course, the more space, the better.
Also. You can help lower the resonant frequency of your floor by applying a 1/2" layer of particle board, then a 1/2 layer of a product called firtex. Then put what ever flooring material you want over it. With the addition of a 5/8" layer of drywall, this is an excellent studio wall too. If done on both sides of the wall, with a 6" gap between the two sides, and offset studs, you will get about 75db of attenuation.