Some observations.
Low frequencies (let's pick on 80Hz and lower) cannot be localized by mechanisms of human hearing. When listeners believe they can localize these low frequencies, the localization mechanism is, in fact, the higher frequency artifacts (or the placebo effect) of the subwoofer's generation of the low frequency output (driver slapping the air, etc.). When these high frequency artifacts are eliminated and the listener has no advance knowledge of the physical locations of the low frequency drivers, they cannot be localized. There is therefore no advantage associated with keeping the subwoofers in the same place as the mains. In fact, due to the differences in placement to achieve proper imaging and the modal response characteristics below a room's Schroeder frequency, they cannot be colocated.

Meridian would suggest, using their speakers that speakers (such as the DSP8000s) should be set to large. Let's examine that. The DSP8000s are said to produce 20Hz to 20kHz at 118 dB SPL at 1 meter. That would mean at 2 meters a single 8k cannot produce reference in the low frequencies. At 2 meters, that would be approximately 109 dB. With three 8ks, you'd be back to 118 dB. (I am not being critical of their design ... I happen to like those speakers.) Looking at the SW5500, they are rated at 110dB SPL at 1 meter .... ie, they will not produce the full dynamic range at 1 meter. So accounting for a 6dB loss for each doubling of the distance, it would take several to produce reference (115dB at 20Hz). Certainly for most music content, that's fine but note when we did Previn and the Atlanta Symphony's 1812, there was 10Hz content on the masters.

I should add, the fact that a single DSP8000 has four low frequency drivers does not mean the rated output of the 8k is four times the published rating for the speaker.

Finally, one does need to utilize care in the selection of subwoofers when multiple subs are being used in a single space. Subwoofers, as do all speakers, have an optimal range of operation. As much as you do not want subs operating near, or at peak, you also do not want them operating below their optimal curve.




Imagine what you could do if you could do all you imagine.