no, there's no buffering in mix.out_~ only a glitch protection (when turning the level to 0 quickly) and a [hip~ 10]. of course, if you don't use the state saving of pdmtl and no gui, there's no reason to use mix.out_~. i cannot reproduce the glitches you got with sample.play~ or sampler.play~ if your sample is not too big, send it to me by email. pat