Since you have a 360, I've been most recently impressed by the sound in Frontlines: Fuels of War and Undertow (the underwater live arcade game.) Frontlines has nice tight explosions that make my EP600 punch me in the gut and one of the sniper rifles quite simply cracks the paint in my room (muahahahaha), and Undertow has a lot of deep surrounding underwater effects that sound really good. (tho not the voice-acting)