[Alextaastrup]

The best way is to switch off the crossovers on the amp and use them only on HU. I will recommend 63Hz instead of 50Hz for 6,5' midbass.

 

[Alextaastrup]

I will stress out that the playing diapason for a speaker should not include its own resonance frequency, at least 1 octave away. Then it will play cleaner. 3 way system is better in this way, as it allows to choose right crossover points for a set of component speaker system.