A guy over on the Ableton forum made a youtube video that demonstrated that you can push your tracks into the red (over 0dB) in a 32 bit float daw and not incur any distortion into your audio signal.
This was kind of eye opening as I always thought that anything above 0dB in the digital world was bad.
http://www.youtube.com/watch?v=oipad34MYn4
note, make sure your volume is turned down when he starts the test tone.