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stereo channel swapper device, maybe with a stereo vu-meter in it with slow peak lines
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non-clicking W00/WFF changes (they click when the sample is playing while they occur)
That is because the sample buffer is altered during the applied changes. There are more effects that suffer this behavior.
The majority of these effects already getting fast fades applied to the buffer around the changes so the clicks are less noticeable or when in luck, not noticeable at all, but besides that this might as well pull out the punch from your samples, it is not in all cases 100% preventable.