The pan law on the MIO Hardware is “-3dB”. Also known as “Equal Power”.
Hard panned channels are unattenuated.
Center pan channels are attenuated by -3dB and sent to both left and right.
Attenuation in the left output channel varies smoothly from 0dB (hard left) to -3dB (center) to -∞ (hard right) via a cosine gain curve (argument = 0 for hard left, 45° for center, 90° for hard right). The right channel is the converse.