What is a good safe level to set maximum output to when mastering for a CD?  I've been setting mine pretty high at -.3 dB in Ozone8 (which is the default on its maximizer when using "Mastering Assistant"), but my new interface's meters show sporadic red at that level and the manual says I may be overloading the A?D converter.     Any rules of thumb to follow?  Should I back it down to -.5 or even lower?  I frankly don't even hear any problems when I work at -.1, but then my 67 y/o ears aren