To much bass, really


I have the Lehmann Black Cube SE II Phono Amp.
The problem is I'm getting way to much bass. I've played with the switches under the unit and to know avail.
Do I need to go inside the unit to adjust the bass?
My set ,Rega P5 , Dynavector 20x2 Low Moving Cartridge. 
Hopefully someone can help.
trip
If you don't mind, trip, we're curious to know how you got it straightened out.   Thanks.
By adjusting dip switches 3,4 before the output stage and switches 5,6 after the output stage. Trail and error with on and off settings till the base was less boomy.
My error was that I was not adjusting dip switches after the output stage correctly.
Many configurations to work with to adjust bass.