As noted in #8, set_calc_function also calls (mCalcFunc)(this, 1);.

Whether or not this is the right approach (I'm thinking probably not for the reasons in #8, as well as other Ctor/initial sample related concerns), the result is that the BoringMixer example initializes the first sample of output twice:

It would be great if the examples showed either a consistent way of initializing the first sample (if there is a consistent way), or, more likely, be explicit about when you need to use SETCALC, set_calc_function, as well as next(1), or directly set ZOUT(0). Though I realize that a larger, possibly unresolved issue.