I recently found a pair of Bose model 21 bookshelf speakers for $25 to use as B channel speakers and stacked them on my old Wharfdale W60's. This bizarre combo (run through a Sansui 880), when run as A and B helps brighten the sound and detail at low to medium volumes, where the Wharfies are a tad bit muddy. Then, at rock out volume or with classical, I switch off the baby Bose (I never run the Bose alone 'cuz they kind of suck). Does anyone know when the Bose model 21 bookshelf speakers were released?