Turn it down to 1/4 or get a new wife!

New House? (From what I hear new wives are expensive.)

On a more serious note, if your subs are shaking the house, you are probably mixing too loud. Get an SPL meter (Radio Shack has a reasonable one). This will help you mix at consistent volume levels. It will also help you push the volume down bit by bit until it is as low as possible. Someone gave me what I consider a good piece of advice - mix at as low a volume as you can stand. You are not trying to enjoy the music when you mix; you are trying to hear everything as clearly as possible. That usually means relatively low volume. Yes, as some point you want to listen to it at high volume, but that's the stage where you are listening to it in your car, on a crappy stereo, etc. to see how the mix translates to other environments.

The other issue IS your house. Ideally you would like your studio to be acoustically isolated. Unfortunately, this is a very expensive and labor intensive proposition. Check out the Acoustics and Design forum and get Rod (the mod)'s book. Personally, I wouldn't do anything for isolation on existing construction. The book will tell you how, but it's a lot of work.

It's a wood framed floor right? Sub in the corner? I'm gonna gamble and say your upstairs.

Aw damn, you typed "subs"! That's like more than one?

All bets are off:)

Even if the sub is isolated from the floor it will still fire out the frequencies that annoy our neighbors and wives. Then you have to stop them with your walls and your floors.

But isolation is what you want.

As an aside, as I remember it, old wives are expensive:)

New wives are more accomodating. But then what is a musician without a girlfriend if not homeless?;)

edit: This information:
Controlling the transmission of Impact sound through floors comes highly recommended by someone highly recommended.