I'm working with single cycle waveforms which don't seem to work with Preview. The stop/start is done before audio is produced. I'd like a tool that offers an improvement on the native playback. Anything out there? I'm familiar with Iced Audio Audiofinder but that is a bit excessive for my needs.
For simple, reliable audio playback, I actually still use QuickTime.
If you don't like QuickTime X that is included on all new Macs (and I don't), you can still get QuickTime 7, which also has available some very worthy "Pro" functions, for a $30 activation key. Looping should work without Pro.
QuickTime Pro 7 is still highly useful to me even after all these years--the reason it is still around is because QuickTime X was a complete rewrite that matched with Apple's new style for its media applications, but it did not contain all of the features that are present in QuickTime 7.
For looping, I would use Logic if you have it. if not, Garageband will do the job.
For simple audio playback there is always iTunes and a host of alternatives, such as these listed here: http://www.head-fi.org/t/539740/mac-os-x-music-players-alternatives-to-itunes.