| From the instruction manual:
"REFLEX-TUNE
In this mode the V256 works as an automatic pitch corrector and will quantize the dry vocal pitch to nearest note depending on the scale and key set by the user. When the PITCH knob is fully CCW, and there is no external instrument being played, the V256 will quantize to a chromatic scale. If there is an external instrument being played, the V256 will determine the key based on the chords being played and will quantize to the determined key in a diatonic scale. To revert back to the chromatic scale, turn the PITCH knob to noon and back to fully CCW. When the V256 is in chromatic mode, only the REFLEX-TUNE LED will be lit.
As the PITCH knob is turned CW, a different combination of LEDs will light depending on the position of the PITCH knob. The combination of LEDs indicates the diatonic key scale setting for the V256. The table in the “controls” section, under “PITCH” explains which keys are represented by the LEDs.
The BANDS knob controls how fast the pitch changes from one quantized note to another. Fully CCW is the slowest change and creates the most natural sounding performance. At noon the quantized notes are changed instantaneously with no vibrato, creating the most dramatic effect. At fully CW the note changes are still abrupt but more of the original vibrato is let through."
So, yes it can work with just a mic input (aka, your sax) | 
