The miniDSP and SpeakerPower amp is the best way to go. I would avoid all of the other pro amps in this case due to fan noise...
Every time you double the power you gain 3db, the SpeakerPower will already max out the 20A breaker so there is nothing more that can be gained from power.
Do keep in mind that a 20A breaker can pass 40A for a brief amount of time, 20A is not a hard limit per se...
Burst figures mostly come from the internal bank of capacitors that some amplifiers have (you will notice a distinct lack of caps in the inukes vs a PowerSoft K20 or FP20k...)
Every time you double the number of cones, you gain another 3db, this carries on to infinity even if the wattage stays constant.
It takes about 32watts to push 32 18's to 1mm excursion, but it takes 3200watts to push 1 18 to 32mm's excursion, and both are the same SPL...
If you are limited by power, and you are, then chasing after more-cones and bigger-cones is the way to go.
Originally Posted by subbuilds
If handheld paper brochures flutter 12' feet from the sub that would be acceptable even if it can't be felt in the whole room.
That will require about 32 18's ported or horned to 10-15hz...
Every octave lower, gets 4x harder to produce (and 4x the equipment/price needed.)
1hz is 4x harder than 2hz
2hz is 4x harder than 4hz
4hz is 4x harder than 8hz
8hz is 4x harder than 16hz
16hz is 4x harder than 32hz
To make lots of low bass requires a LOT of displacement (which is cone area x excursion) [+ port displacement if applicable...]
To hear 20hz requires a minimum of 70db @ <10% THD.
To hear 10hz requires a minimum of 100db @ <10% THD.
These are minimums, not maximums...
The threshold for ear damage at 1-5hz is ~190-170db.
The threshold for ear damage at 5-10hz is ~170-160db.
The threshold for ear damage at 10-20hz is ~160db.
You won't be anywhere near these levels... so sky is the limit.
Every time you double the distance between the cones and your ear, you lose 6db.
That said, if you get too close to the sub you will be in the nearfield zone where ULF is weakest....
in many cases you will find that walls, ceilings and floors amplify the bass louder (it can also cause them to null out.)
I would highly recommend a CSL UMIK-1, those are professionally USA calibrated from 5hz to 25khz +-nothing, they are <$100. The stock UMIK-1 is 10-20khz, China calibrated.
It terms of making low-bass, nothing beats a 24 or RE-18. It's all about woofing as much air as possible.
The rest is box optimization and placement optimization.
The miniDSP can EQ and XO to at least 10hz, so you should be good there. Most other products stop at 20hz.