Need advice on how to sound insulate my room

Lead wall paper. Yes, there is such a thing, but expensive. Often used as an underlay in floors. I used it in a media room that I built some time ago. It needs to be sealed as it could be an environmental hazard. If you have children, forget about it.

You might want to look at the tread on building a home theater on AVS forum. This is a very common topic in building a theater. Insulation is not a very good insulator. You should look at applying another layer of drywall, especially in the ceiling, using Green Glue between the layers. It is not really a glue, but a viscoelastic material that dissipates the sound. The Sound Proofing Company has a lot of material on their website on how to approach this problem. Ted White from their is active on the AVS forum. The bass is the hardest problem and low bass is almost impossible to totally block without a lot of rebuilding. But a Green Glue ceiling will greatly help the problem and will not reduce the ceiling height by much.

Dtc is on the right track - to stop everything down to about 500Hz, another layer of drywall (preferably 5/8"), with copious amounts of Green Glue would be a good start. Sound is like light, and if you seal up your listening space, you can achieve decent attenuation. Lower frequencies are much more difficult - really the only way to stop them is with massive reconstruction. Mass and stiffening will only go so far (bass will pass through a 6" cinder block wall with no problem if the sound source is on the other side of it); what you need is acoustically dead space and that may not be attainable given your current situation. Good luck.

I'd recommend the book Premium Home Theater by Earl Geddes, and the concepts apply to stereo as well. I bought several books on the topic but found this one to be the most useful and an easier read. His approach addresses bass without dampening out higher frequency detail, which sounds like a concern of yours, and unlike most of the other books he recommends actual products which I found very helpful. Best of luck.

Have you tried de-coupling the speakers from the floor? had a similar problem and proper stands with Blu-tack helped quite a bit.