John does a great tutorial on how to created properly looping samples for use inside of samplers like the one found in PluginGuru Unify and Spectrasonics Omnisphere 2. Using the free Endless WAV, John goes over how to bring up a sample and properly loop it so you don't have any clicks. If you are creating custom samples for Omnisphere 2, this is the app and the tutorial you will want to use (and master). I use it for all my custom samples. You will not get this kind of result using Apples AutoSampler found in Logic and MainStage.