First,theyallowyoutouseeffectsinaparallelfashion,blendingthemtogetherinsteadoffeedingoneintotheother.(Uptotwoparallelloopscanbecreatedusingtheonboardmixers.)
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First, they allow you to use effects in a parallel fashion, blending them together instead of feeding one into the other. (Up to two parallel loops can be created using the onboard mixers.)