I have read through most (all?) of the similar topics on this subject; and have come down to a couple of choices:
1. build a center channel using an 8" AR woofer, mid range and tweeter from an AR91.5 in a cabinet with similar volume and geometry to an AR18/28; with the same crossover as the upper three drivers in an AR9, but no hi-pass filtering for the 8" driver.
2. Parts Express Triune: http://www.parts-exp...?project=Triune
I just picked up a pair of AR91 this weekend, my wife likes the teak on the cabinets, unfortunately one of the mid ranges is non functional, so the AR91.5 that we have had for years will be sacrificed to get the 91s going. Which lead to me thinking about further use of the components.
And then there is the LFE...... 2X AR 12" woofers in a box - AR9 without the small drivers.... I'll set the receiver to large speakers, and the LFE crossover as low as it will go, to get the full effect (not the -10dB as mentioned in another topic).
FYI: after being stuck in a small apartment for the past 4½ years, we are now in a house 
