CNET reviewed the SP-BS21-LR bookshelf speakers as part of Pioneer's SP-PK21BS 5.1 speaker system. While the SP-BS21-LR speakers weren't directly compared with other two-channel bookshelf speaker systems, the full 5.1 system offers outstanding sound quality for the price.
For more information on the SP-BS21-LR speakers, read CNET's full review of the Pioneer SP-PK21BS.