C-Media 6632A (Xonar U7), 'Input Gain Pad Control'

I have a Xonar U7, with a C-Media 6632A. It works somehow, the only issue i have is that the control 'Input Gain Pad Control' is kind of odd: By the control name i would expect it changes the gain on the input path, but in reality it changes the headphones output level. The Line output level is constant, as well as the input level. Alsa settings are: Line capture on Mic capture off Item0: 'Line'

Is this Xonar U7 specific or is this a general implementation bug??

best regards