6 Channel Velleman Audio Mixer

I’ve got a 6 channel velleman mixer given to me from back in the day.It works fine, but there’s is one problem with.The line input stages are much to sensitive for todays CD’s, with the input gain potentiometer completly closed it still clips.You can see it on the red led (overload) just above the fader.How can i change that without changing the input impedance.The input stage consist of a 180pF cap to ground followed by 1µF serie cap, followed by serie resistor 33K, followed by 15K to ground, en this goes than in the NE5532 opamp.So i need to change the values of the 33K and 15K resistors to keep seem impedance but lower the sensitivity.Can anybody calculate this?