Wave Volume should be set to 1.0 (full volume), Output Volume should be around 0.5 if it affects the signal level - line outputs usually are not affected by this control, headphone or speaker outputs usually are. REW will set these controls to their last values on startup if the Control output mixer/volume check box has been selected and REW has been able to access the controls, otherwise you can set them manually as required, via the controls above or those in your soundcard's mixer or OS audio level controls. If the output volume control does not affect the output being used it is best to mute it, that prevents any sound from your computer's speakers affecting your measurements.
The input level, if not using a USB microphone, should be around -18dB FS when the cal signal is playing, if it is lower or higher adjust the Input Volume either using the REW control (if enabled) or your soundcard's mixer or OS audio level controls. The target range is -24dB to -12dB FS. Levels higher than -12dB may result in input clipping during measurement, levels lower than -24dB give noisier results. If you are using a USB microphone leave the volume control at the unity gain setting, which is selected by default when the mic is first plugged in.
Press Next to start the calibration signal or Cancel to quit.