Note: Looping instrument samples is an art. It is very easy to make loops that click, warble, pop or just sound plain awful (nothing is not broken). Clicks are caused by the sample amplitude at the loop start and end points differing (try to select zero-crossing points and the same phases of the waveform, that is moving in the same direction). Another source of loop disasters are slow changes in timbre, phase or frequency content. Normally these happen slowly and naturally and add motion to the sound, however when a loop jumps back to a distant point, the abrupt change sounds like a glitch. In these cases the 'Bounce' loop can be a solution. In conclusion, there is a reason why professional sample libraries are expensive, someone (or team) had to sit down and craft hundreds/thousands of loops, often involving serious post-processing (layering, cross-fading etc). If we haven’t scared you off by now, experiment with the loop types and start/end positions and remember some sounds just don't loop smoothly...on second thoughts perhaps we should only allow trained professionals access to these controls?

Tip: Use 'Set Optimal Loop' command from sample editor popup menu (right-click on sample editor wave display) to assist in finding good loop points. This jumps the loop-start/end markers between zero-crossings. Don't forget to zoom the wave-display if you need finer control.