Polk Audio Signature Series S20 Bookshelf Speakers (Pair) Signature Series: Polk designed its Signature Series of loudspeakers to bring a big surround sound and a live music experience into the comfort of your living room at an . Featuring Hi-Res certification with a new high-resolution Terylene tweeter, redesigned Dynamic Balance drivers, precision crossovers, an anti-diffraction magnetic grille, modern cabinet styling and exclusive Power Port bass enhancing technology, Polk's Signature series loudspeakers deliver crystal clear highs, detailed midrange, and deep bass; plus they look great in almost any decor. Built to bring the big surround sound theatre and music experience into the comfort of your living room, the Polk Signature S20 bookshelf speaker continues in the Polk tradition of American HiFi. Featuring Hi-Res certification, a new Dynamic Balance designed acoustic array, precision cross-overs, an anti-diffraction grille, modern cabinet styling and exclusive Power Port bass enhancing technology, you get elevated sound for movies, TV and music in a totally re-imagined design. Polk-expect great sound. Dynamic Balance Drivers: Dynamic Balance is a proprietary Polk Audio technology using laser imaging to determine what combination of speaker materials create the least amount of resonance. Eliminating resonance in speakers results in a wide, smooth response and low distortion. Using just the right materials enables Polk to eliminate issues that reduce speaker performance and tune out performance-robbing resonances before they occur. Dynamic Balance ensures a rich, clean, full-range sound no matter what you're listening to. The Polk Signature S20 bookshelf loudspeaker incorporates a Dynamic Balance two-way driver array with one 1" tweeter and one 5.25" woofer.