The Super Zero is one of the great all-time "honest" satellite designs. -6 dB @ 80Hz and flat, flat, flat out to 20KHz with a terrific, virtually notch-free polar response.
I've got a trio of the powered versions, the M-00s, on the way for a full Audioholics review. If you need some passive left-center-rights or right or left rear satellites (for a 7.1 system) you can't go wrong with these passive classics.