It doesn't record sound properly when you use ofxSoundRecorderObject with the settings like below.
settings.numInputChannels = 2;
settings.numOutputChannels = 4;
...
input.connectTo(recorder).connectTo(mixer).connectTo(output);
recorder.startRecording(ofToDataPath("test.wav", true), true);
The number of channels of the recorder forced to change to 4 and its sound goes noisy.