Classe Sigma SSP and Rel S3 connection issue

I used both inputs which is recommended by Rel. I have my center and surrounds speaker Xcross over at 60 and 80 hz respectively. Then front left and right set to full. This is what rel recommend but I lost all mid bass. Then I change the front speaker to cross at 60 hz but still have the same results. Rel said this is what need to be done but Classe said no.

My main front left and right are B&W 804s and center is also B&W htm3s. They are cross at 60hz. There are no sub out cross over in the Classe. The Rel speaker level cross over for the main speakers is cross at around 40hz. When I listen to stereo music using just the main with the speaker level input, bass are fine. It is just that for 5.1 listening, even we set all speakers to small and let them cross over to the sub out, the mid bass is not that good. I think is something to do with how Classe handle bass management. Quite disappointed with the Sigma SSP.

I have tried that scenario as well,have all speakers cross at 60hz which mean only the LFE input and sub out are used, but mid bass is still missing. The only way I got full bass is disable sub out at the ssp and set main speaker to full. This way all the other speakers will send their bass info to the main speaker and the rel support the bass under 40 hz. However I don't like this setup because it will put an extra load on my amp. What I don't understand is why I still can't get full bass from the ssp using sub output and the rel LFE input, and have all speakers cross at 60 hz?