Experience movies, music, and games in high-resolution, room-filling cinema sound with effortless bass. The powerful ES20 bookshelf speaker from Polk is Hi-Res Audio certified and features an acoustic array with Dynamic Balance, precision crossovers, and Power Port technology for enhanced bass. The Hi-Res Audio certified Terylene dome tweeter of the ES20 delivers crystal-clear highs (40+ kHz) for high-resolution music from services like Apple Music, Tidal, Amazon Music HD, Qobuz, and Spotify HiFi, as well as the soundtracks of the latest Ultra HD movies. Polk's patented Power Port design provides greater surface area and smoother airflow for more power and less distortion compared to speakers with traditional bass reflex ports. Combined with the robust 6.5-inch woofer of the ES20, this results in effortless bass that tickles your belly. Thanks to the acoustic array with Dynamic Balance and phase-optimized precision crossovers, the Signature Elite ES20 ensures a seamless, realistic soundstage regardless of your listening position. The ES20 impresses with clear, room-filling, and realistic sound reproduction for virtually any amplifier or receiver—from classic 4 or 8-ohm audio systems to the latest surround sound AVRs with Dolby Atmos and DTS:X. Driver configuration: 1" (2.54 cm) d (Round) high-resolution Terylene dome tweeter, 6.5" (16.51 cm) d (Round) Dynamic Balance glimmer-reinforced polypropylene driver. Total frequency response: 44 Hz → 40,000 Hz. Sensitivity (1 watt @ 1 meter): 88 dB. Crossover frequency: 2,500 Hz. Recommended amplifier power per channel: 20 watts → 150 watts.