I'm with Warrenh for the most part, but I would say it depends on what you are coupling with. Hardwood floors (especially those without adequate subflooring) move around a lot so decoupling might be the best bet in your case. There's really only one way to find out for sure and that's to experiment!
As far as the acoustics being altered with the new floors- chin up! Some of the best studios in the world implement a little audio action with brick, stone, wood, and other reflective surfaces to liven up an otherwise dead room. It isn't exactly a reference attribute with regard to playback but it can often make for a more enjoyable system so long as it's not too out of control. A large rug and your furniture along with the wood floors might just end up being an improvement over carpet alone.
Good luck.
As far as the acoustics being altered with the new floors- chin up! Some of the best studios in the world implement a little audio action with brick, stone, wood, and other reflective surfaces to liven up an otherwise dead room. It isn't exactly a reference attribute with regard to playback but it can often make for a more enjoyable system so long as it's not too out of control. A large rug and your furniture along with the wood floors might just end up being an improvement over carpet alone.
Good luck.