Unfortunately, I have to be the bearer of bad tidings here: There isn't really much you can do from above, apart from actually floating a new floor. But as you saw in the link I gave you about that, floating a floor on an upper story in a building is not a simple proposition at all, and certainly not cheap, even assuming that the structure underneath has the ability to support the large amount of mass that you need. All you can really do is to add mass to the existing floor, by putting down several layers of thick MDF or OSB, but then you are limited by Mass Law, which is a law of physics that is not very friendly: it says that if you double the mass, then you get a 6 dB increase in isolation. So if you start withe one layer of OSB, then add as econd layer you get 6 dB more. Add another TWO layers for the next 6 dB, then another FOUR layers for the next 6 dB, etc. Not fun. With mass law alone, you run out of structural integrity (and money!) long before you get to reasonable levels of isolation. That's why mass alone is not the best way of isolating: Mass + mass decoupled by a resilient "spring" is the way to go for high levels of isolation. It's a whole different ball game. In your case, it's very easy to do from below, but not easy at all to do from above.
Is there no way at all that you can do this from below? Whoever owns that place downstairs surely would not mind you guys going in and giving them a brand new ceiling installation, for free! Especially if they will benefit from the increased isolation just as much as you will. Maybe you could talk to them, and see if they are open to the idea? If someone came to be and offered to replace and re-paint my ceiling for free, and it would even make things quieter to boot, I think I'd be inclined to listen...
Failing that, you don't have a lot of choices: floating your floor is the only real solution.
You might also find these helpful:
http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir802.pdf
http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir811.pdf
(that one is probably the most comprehensive study on floor isolation systems ever done, that is available publicly).
http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir766.pdf
(also excellent)
Not exactly light reading, but very informative, and very pertinent to what you guys are trying to do, I think. Those are pretty much the definitive studies on the subject of floor isolation.
The only other thing thing that might work to a certain extent, is the "drum riser" concept but extended to the entire floor: cover the entire floor with 2" of OC-703, then put two layers of 19mm MDF or plywood on top, screwed and glued, but carefully cut so that it does not touch the walls: Leave a gap of about 5mm all around the edge, and fill that with acoustic caulk. That's not a proper floated floor, just a partly decoupled, partly damped floor that MIGHT work for you. At least it will help with the impact noise, even though it won't isolate fully.
Sorry I can't give you any better news than that, but the universe is created in such a way that the laws of how it works are immutable, and no amount of hoping or frustration can change that: The laws of physics are what they are, and their are no magical materials that can bypass those laws.
But regardless of what you do, I'd still get a structural engineer to take a look at that floor, and confirm how much extra load you can put on it safely. Your studio is going to weigh a huge amount, considering the level of isolation you are seeking, so you MUST make sure that the building structure can handle that, and if not then beef it up sufficiently that it can.
- Stuart -