The KEF KASA500 is a dedicated dual-channel Class D amplifier engineered to drive KEF’s Ci series in-wall and in-ceiling subwoofers. Delivering 250 W per channel into 4 Ω — or 500 W bridged into a single 8 Ω load — it provides the headroom needed to extract deep, controlled bass from compact architectural enclosures where passive amplification is not an option.
DSP Control and Crossover
At the heart of the KASA500 is a DSP engine that manages crossover, protection, and equalisation. The low-pass crossover is adjustable from 40 Hz to 140 Hz with a software bypass mode, and the unit offers DSP-configurable pass-through with optional high-pass filters on the outputs. KEF provides pre-loaded EQ profiles optimised for specific Ci subwoofer models, and the DSP firmware can be updated via the KASA500 Programmer utility to add support for future speakers.
Flexible Inputs and Operating Modes
The rear panel accepts stereo RCA line-level inputs, a dedicated mono LFE RCA input, and stereo speaker-level inputs, making it compatible with virtually any AV processor or integrated amplifier. Switchable operating modes cover stereo and mono configurations, two-channel and bridged output, line-out EQ or pass-through, and a choice of manual, music-sense, or 12 V trigger activation. The 12 V trigger input accepts 8–14 V at up to 50 mA via a 3.5 mm jack, with support for both tip-positive and tip-negative polarity.
Installation
The KASA500 is housed in a slim chassis measuring 88 × 432 × 304 mm (H × W × D) without feet. Optional rack-mount ears are included, allowing it to occupy a standard 2U EIA rack space at 88 × 483 × 304 mm. Its Class D topology keeps heat output and idle power draw low, with standby consumption below 0.5 W.
Compatible Subwoofers
The KASA500 is the required amplifier for the Ci3160RLb-THX in-wall subwoofer and is specified for active-mode operation of the Ci200QSb-THX and Ci200TRb in-ceiling subwoofers. It can also be used with other KEF Ci subwoofer models that fall within its power and impedance range.
| Amplifier Type | Class D |
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| Channels | 2 |
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| Power Output (Stereo) | 2 × 250 W into 4 Ω |
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| Power Output (Bridged) | 1 × 500 W into 8 Ω |
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| THD | <1% |
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| Crossover Frequency | 40–140 Hz (adjustable, software bypass) |
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| Line-Level Inputs | Stereo RCA, Mono LFE RCA |
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| Speaker-Level Inputs | Stereo |
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| Operating Modes | Stereo/Mono, 2-Channel/Bridge, EQ/Pass-Through, Manual/Music Sense/12 V Trigger |
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| 12 V Trigger | 8–14 V @ 50 mA max, 3.5 mm jack |
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| Standby Power | <0.5 W |
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| Dimensions (H × W × D) | 88 × 432 × 304 mm (without feet) |
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| Dimensions (Rack-Mounted) | 88 × 483 × 304 mm (2U EIA) |
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| Weight | 5.76 kg |
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