Hi Lance, As mentioned Protools has a POW-r dither plug-in module, so does BIAS Peak
www.bias-inc.com which is like a 2 track editor for Mac OSX. There isn't a huge range of audio software for Mac that has POW-r. I am still waiting for Waveburner Pro OSX to become a stable program to do my POW-r needs. Until then I use Waveburner Pro in OS9 on a dual boot system to use POW-r & CD burning etc.