Refer to my suggestions on how to route grove into, and fill the edge of a door with felt back in your "lair" thread. That'll get you plenty of sound proofing.

Solid core fire doors aren't cheap, but still much cheaper than those things.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs