Overtone/Clojure samples can be played on top of themselves with no clicking.

sound_testing.clj

(use 'overtone.core)
(boot-server)
(def samp1 (sample "power_melody.wav")) ; see http://alumni.soe.ucsc.edu/~mds/amp_testing/power_melody.wav

;;; Play the same sample a bunch of times with overlap
(loop [n-remaining 10 delay-to-use 0]
  (after-delay delay-to-use samp1)
  (if (> n-remaining 0) (recur (- n-remaining 1) (+ delay-to-use 1800)) '()))

;;; to play the sample once, just enter
;;; (samp1)
;;; at the repl