ELAC Uni-fi UB5 Bookshelf Speaker (Black, Pair) The perfect speaker for both home theater and music lovers alike ; Nominal impedance: 4  ; minimum 3.4 True 3-Way Design delivers more accurate sound than more traditional 2 -way designs. Frequency response - 46 to 25,000 Hz. Sensitivity - 85 dB at 2.83 v/1m Custom designed concentric driver provides much better imaging and performance compared with standard configurations used by our competitors Dedicated 5  aluminum woofer delivers powerful bass in a small package. Recommended amplifier power: 40 to 140 wpc A sophisticated crossover design combined with a sturdy braced cabinet helps deliver an audio experience far beyond its price point.