I think you're talking about "double bass" or equivalent because you want MORE BASS in your system.
Many AVR and Pre-pro have this type of feature.
However, if it were me, I would just set all speakers to small and let the Subwoofers take all the beating.
When I owned big towers like Revel Salon2, B&W 802 D2, and Philharmonic 3, I always set them to small and let my subs do all the heavy lifting.
I don't think is a hard and fast rule on that. I have been tweaking my main system lately. It sounds and measures best with all speakers except the ceiling set to large. In the last room the best results were with the crossover set to 60 Hz in this room it is 40 Hz. I did listen to it with full crossovers at 40Hz. However it does sound better with the LFE + main setting. The sense of space is increased. That may be because all bass frequencies are sent to the big line and in stereo mode because of my active BSC system. The woofer outputs is also blended obviously which is mono.
I have been really lucky with this room. It sounds and measures well. There are no significant bass drop outs or peaks anywhere. The only thing is a slight rise in response in the 25 to 20 Hz regions. For some reason the highest level is at 20 Hz. This is all excellent as it means the crossover from the center, midlines, surrounds and rear backs is largely acoustic. So the time delay is minimal phase shift. All the f3s are in the 35 to 45 Hz region, except the surrounds at 52Hz. an added bonus of the lower crossover is that the slight peaking at the acoustic handover of the two lines in the main speakers is now gone. This was at 40 Hz.
The effect is excellent. This room seems easier to pressurize in the bass, even though it is bigger, I think because the room has less bass leakage and above all is more solid by far. In addition there is heavy damping below the floor and behind all walls. Two of the four walls are concrete, but there is deadening material between the sheet rock and the polystyrene ICF blocks over the concrete. I did this because concrete does not have the best sonic adsorption pattern and polystyrene resonates violently at 1000 Hz. Since this was new room I was able to set the dimension ratios. It seems to have worked for me.
The room is very neutral and so makes speaker evaluation easier and more reliable. I'm convinced in a room like this you can keep the sound coherent and minimize time shifts which you can't do with high order crossover and physically separating bass fundamentals from their harmonics. This latter is something that Ted Jordan was always pointing out and I believe him to be correct about this. Getting all this right does provide a big added measure of acoustic space and depth.
