Unless you have a huge room, dual SVSs will definately be overkill. I've got the same Axioms as you mated with a SVS 20-39PC+. This is in a 15' x 15' room that is open to my kitchen. I'm running the SVS about 6db hot, and that's at 10% gain on the sub's amp. The bass output of this sub is incredible, and frankly more than I could ever use without moving to a much larger room.
Although I can't directly compare my SVS to the ACI unit, I can't stress how happy I've been with the SVS. I would highly reccomend both the company and their products.
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