Oh great. I asked several people to calculate it, but nobody helped me.

The dimensions in cm are: 34x22x14 (internal). The speakers are 10cm. Minus empeg, amplifier (15x15x2,5), psu (12x6x3).

The back panel is about 1cm deeper, have no picture of it now.
The amplifier is in the middle under the empeg. I have put some damping material on top and bottom and between empeg and speakers. The psu is now between a speaker and empeg but i will put it in the middle top.

If i think right the circuit should mix together both channels on low frequency? Can u give a schematic?