3. The Final Simple Answer Wait, what ? Didn't I just say it didn't matter, provided you don't clip ? A little more detail Any of the three answers above will work out fine for you. But there are still good reasons for leaving more, rather than less headroom: It does no harm . At 24-bit resolution, you've still got a huge signal-to-noise ratio, so there's no need to max out the peak level in the mix. Play it safe ! Even a massive 12dB of headroom will sound excellent. It may avoid problems . As you get close to 0dBFS, the risk of "inter-sample" peaks crops up -- especially with heavily processed, in-the-box sounds. These inter-sample peaks may add distortion at a later stage, so it's best to avoid them. Analogue "emulation" plugins will distort at a much lower level, even in 32-bit floating point. Let's look at that last point in a little more detail. One of the things we like about analogue gear is the soft saturation distortion it can add when you push it hard. And plugins that emulate this effect do the same. So if the whole mix is running up into the red on the channels, and you're using some processing that works in this way, you may end up with much more saturation and distortion than you intended. Better to stay on the safe side and keep the levels lower to avoid this happening by mistake. And that means running all the channels