[Jackaudio] Headroom.

Dear All, I am developing a software synthesiser. My question is about how much headroom I need to leave. My understanding is: 1. The audio range is from -1.0 to 1.0 (yes/no?). 2. Anything above 1.0 or below -1.0 will be clipped. 3. If the audio interface is 16 bit, then -1.0 corresponds to -32768 and 1.0 corresponds to 32767. 4. If I play a note on a synthesiser and it generate sine wave from -1.0 to 1.0 then this is no good. I need to divide it by some number to leave a headroom. 5. The question is, how much headroom I need? Any help would be appreciated. With kind regards, Robert