Hi Madp,
I would say when setting up your sub+speakers it is all a matter of taste and also alot of trial and error as there are other factors to consider aswell, like the room as it can have a dramatic effect on the bass frequencies with the positioning of the sub.
If i was you i would let the amp/processor handle all the bass management so therefore set the Rolloff on the sub to as high as possible so that is not working and any other setting that will interact aswell to off.
Then try setting the Xover on the amp to try and get the best sound or one that you prefer usually about 80hz but as your MA s6's go alot lower maybe try a lower setting and also you do not have to have them set to large if it sounds better when the speakers set to small.
Again it is all about trial and error and getting a sound thats right for you
Hope this helps alittle
John
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