Subwoofers.... one 10" or two 8"?

To anyone interested, I repeated the out of phase/phase setting experiment using the on-line tone generator posted above and a Radio Shack SPL meter positioned approx. ear level at the listening position.
I ran measurements from 200 to 10 HZ for the Silverlines alone with volume at 200 Hz set to 80db. Observed values generally less than 70db for 50 Hz and lower (a slight bump to 70 & 74 db for 40 & 35 Hz, respectively). Decibel levels at 80 Hz were virtually identical (i.e., 82/83 db) for 0, 20, 80, 100, 120 & 140 Hz. At 160 degrees, a slight reduction to 80 db was observed. A value of 77 db was measured at 180 degrees. I did not find a huge null created by running the subs out of phase to the main speakers. I wonder if this has to do with the great disparity in speaker sizes (one 12" SB1000 driver vs four 3.5" mid/woofer drivers in the Preludes) or if it is due to "reinforcing" room effects. I did listen to quite a bit of music afterwards with connections properly matched between subs and mains and with the phase now at 180 degrees. Did not notice any of the negative effects previously reported with phase at 140 degrees. Possibly the ("sub") bass was a little better at 180 than at 0 degrees but it was very subtle if not a placebo effect.

You've GOT to be kidding that you're even considering an 8" sub-woofer.  There's no replacement for displacement and even with a 10" driver, you're marginal on the deep end, which is where subs are supposed to operate.  There's a reason they make 12", 15" and 18" bass drivers...

There is also a very good reason for running two subs vs. one.  With just one sub running, you're going to have an uneven low frequency response through your room due to room resonance.  With one sub running, move around the room while music with good deep end is playing.  You'll find there are null and peak spots in different places.   But those will also depend on where the sub is.  With two (or even more) subs, you'll have that tend to even out depending on where you place the subs in the room.

Go for the two 8". They will compliment the drivers in Mirage OMD-15. You want a seamless integration of components that work together to accomplish your goals.  Rel - especially older models will sound more musical. JLs are solid.   

I initially never believed in subs until I read a paper from a professor at MIT on how humans process frequency response. Generally the standard - it lays within 15hz - to 20khz, however there are ambient environmental vibrations that other nerve endings in our bodies / brains pick up that also affect how humans process sound - Therefore extending this actual frequency response to lay within the 10hz - 120khz range.  

If the goal of the audiophile is near perfect sound replication then ... how does one achieve the goal? There are no speakers that can achieve this task alone, and the ones that are somewhat close in one way or another, cost as much as if not more than a house.

I realized that the most economically way to work towards the goal was to invest in Subs as an extenuation of my speakers limitations. I make this obviously sounding statement because I have seen systems where there is overkill that produces Noise, not music. So my two 6.5" mid/bass drivers on each speaker are complimented by a 10" sub driver on each speaker.   
 
There is nothing simple about a 2 channel system. The difference is in the details. Work within your means, enjoy this hobby.