With the two provided gnaural presets, one can either hear annoying clicks or static-like noises during playback. These issues do not appear if the files are rendered to another format, so it is most likely a playback issue.
System tested on:
Arch Linux (normal kernel, 3.6.11)
Gnaural 1.0.20110606 (aur link: https://aur.archlinux.org/packages.php?ID=43882\)
portaudio portaudio 19_20111121-1
Relevant forum post that prompted investigation and has additional details: https://bbs.archlinux.org/viewtopic.php?pid=1215009#p1215009