A single 15" optimally placed would likely have more depth and output than dual 10". The drawback is finding that optimal spot and hoping it's not somewhere awkward to plonk a sub. The 15" is big so bear that in mind.
Duals usually give a better spread of bass throughout the room and two smaller subs gives you a bit more flexibility for placement.
The Monolith™ THX® certified subwoofer sets the standard for bass output, low distortion, and affordability. THX Select Certified: THX® engineers completed hundreds of different scientific tests to ensure the highest audio performance possible.
Those prices with American Audio are still very good if you compare to SVS PB2000 Pro in UK! Looking the data for the 12" model it shows very low distortion figures, guess that is partly cause it has to pass the THX Ultra tests. Performance looks really good for the price, roughly similar performing Arendal 1723 1V costs 1480£.
I assume you have read the Audioholics review of both 10" and 12". The latter seems to be the sweet spot. I just checked AVNirvana`s review of the 12" model. This thing digs deep (in-room response below), Todd pushed it to reference volume and it just kept sounding superb!
[FLOAT_RIGHT] [/FLOAT_RIGHT] [FLOAT_LEFT] Monoprice couldn’t help itself. First, it successfully became the Internet’s go to source for reasonably priced AV cables and interconnects. Now, it’s attempting to crack the foundation of a rather insulated top-end AV marketplace with seductively...
Their prices was as I stated as below but they need to check shipping on the 2 smaller units and only ship the larger 15" version in 4 units per Order.
For the price difference I would be interested in a 15" version maybe 2 and maybe this could work if someone else in the North West wanted 1 or 2 and could collect from me.
10" £363 Inc Del
12" £582 Inc Del
15" £975 x 4 ONLY Plus 10% Discount £877 Per Sub delivered
Here is the Email I got from Karoline from Customer Service.
So we figured out that the Ebay listing's headline wasn't correct for the subwoofers. We disabled the offers for now as we have also a shipping issue with the 15-inch one. The 15 inch with 1000 W has a price of 1,073.34 Euro can be only send in a quantity of 4. But you would get a 10% discount on it for the 4 of them.
The 12 inch with 500 W would cost 640.80 Euro. And the 10 inch with 500 W is 400.50 Euro. I also have to check if there are any shipping restrictions with the two cheaper ones.
If you are still interested in one of them, please let me know and I can further assist you.