I use a pair of Vandersteen 2Wq subs. Since these are fed from the amplifier speaker taps, they are indeed stereo subs. I have them positioned behind and outside the mains. I have no issues with imaging of low frequencies - images are stable in the range covered by the V2qs.
Sub users...
I am considering a sub, I have never used one. Something I wonder about though is, certain songs will have drums playing in just one channel, like track 3 on the Dave Brubeck CD "Time Out", it has a cool drum "solo" in the left channel, and other CD's will have drums that will bounce back and forth between the two channels. When using a sub, does this still sound natural?
Brian
Brian