NEXT PRO AUDIO HFA115S 2 CHANNEL ACTIVE REFLEX SUBWOOFER SPEAKER - HIGH EFFICIENCY. HFA115s – 2-Channel Active Reflex Subwoofer. To further simplify creating active 2-Way systems the HFA112s, HFA115s, HFA118s use an integrated 2-channel digital amplifier to power external full-range passive speakers, for example the HFA206p or X-line.
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