The output is mixed from an array of inputs, linearly interpolating from two adjacent channels.
LinSelectX.ar(which, array, wrap: 1)
LinSelectX.kr(which, array, wrap: 1)
NOTE: all the ugens are continuously running. This may not be the most efficient way if each input is cpu-expensive. The array is fixed at the time of writing the SynthDef, and the whole array is embedded in the SynthDef file itself. For small arrays this is more efficient than reading from a buffer.
wrap does not work yet.