Short answer: the REL Acoustics R-528 is the proven choice, measured and ranked among subwoofers, while the newer KEF KC92 has no independent measurements yet and can only be compared on specs.
What the KEF KC92 offers: Twin 9-inch drivers mounted back to back in a force-cancelling layout that reduces cabinet vibration, driven by 1,000W RMS (2 x 500W) of Class D amplification with KEF’s Music Integrity Engine DSP.
What the REL Acoustics R-528 brings: 12-inch carbon-fiber passive radiator with 500W RMS Class D amp reaches 21Hz.
On paper: The REL Acoustics R-528 is rated down to 21Hz against 200Hz, though makers quote these at different tolerances. The KEF KC92 has more amplifier power, 1000W against 500W.
Price: the KEF KC92 lists at $2,499.99 and the REL Acoustics R-528 at $1,999.
Buy the REL Acoustics R-528 if you want a speaker whose sound quality has been measured and ranked. It also has deeper rated bass.
Buy the KEF KC92 if you want more power, and you can wait for measurements to confirm how it sounds.
Looking for alternatives? See the complete Subwoofers rankings.
Specifications Side By Side
| KEF KC92 | REL Acoustics R-528 | |
|---|---|---|
| Price | $2,499.99 | $1999 |
| Ranked | - | #69 of 145 in Medium Home Subwoofers (30-75 lbs) |
| Enclosure | sealed | passive radiator |
| Drivers | 2x 9” drivers, force-cancelling | 12” (305mm) driver |
| Amplifier Power | 1000W RMS (2 x 500W) | 500W RMS |
| Frequency Response | 11-200Hz, ±3dB | 21Hz-6dB |
| Maximum SPL | 110dB (manufacturer specified) | - |
| Dimensions | 352.5H x 330W x 360.5D mm | 17.5”H x 15.5”W x 17.2”D (444.5 x 393.7 x 436.9 mm) |
| Weight | 20.0 kg | 58 lbs (26.3 kg) |
| Cabinet Color | Black Gloss, White Gloss | - |
| Country | United Kingdom | United Kingdom |
| Output SPL at 25 Hz | - | 92.7 dB |
| Output SPL at 31.5 Hz | - | 106.5 dB |
| Output SPL at 40 Hz | - | 111.0 dB |
| Output SPL at 50 Hz | - | 112.7 dB |
| Output SPL at 63 Hz | - | 114.6 dB |
| CEA-2010-A Average (40-80Hz) | - | 112.8 dB (avg of 3/4 bands) |
| Warranty | - | 3 |
| Measurement Source | - | Brent Butterworth |
Prices on this page were last checked September 29, 2026 at 3:43 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
KEF KC92: $2,499.99 KEF eBay
Older model: the Kef KF92 (rated 3/5).
Pros: Twin 9-inch drivers mounted back to back in a force-cancelling layout that reduces cabinet vibration, driven by 1,000W RMS (2 x 500W) of Class D amplification with KEF’s Music Integrity Engine DSP. KEF rates it at 11Hz to 200Hz (±3dB) from a cabinet only about 35cm on each side. Speaker-level inputs and an expansion port for KEF’s KW1 wireless adapter.
Cons: No independent measurements yet, so its output can’t be compared with ranked subwoofers. KEF rates maximum output at 110dB, modest for a subwoofer at this price, so it suits music and smaller rooms more than reference-level home theater.
Full KEF KC92 review and specifications →
| Amplifier Power | 1000W RMS (2 x 500W) |
|---|---|
| Cabinet Color | Black Gloss, White Gloss |
| Country | United Kingdom |
| Dimensions | 352.5H x 330W x 360.5D mm |
| Drivers | 2x 9” drivers, force-cancelling |
| Enclosure | sealed |
| Frequency Response | 11-200Hz, ±3dB |
| Maximum SPL | 110dB (manufacturer specified) |
| Weight | 20.0 kg |
- Links
- Reviews, Comparisons and Sound Samples
- These figures are manufacturer-specified rather than independently measured.
- Head-to-Head Comparisons
REL Acoustics R-528: $1999 eBay
Pros: 12-inch carbon-fiber passive radiator with 500W RMS Class D amp reaches 21Hz. Fast impulse response best in REL series. Breathtaking bass reach and low distortion in compact package. Speed and detail-oriented musicality. Premium fit and finish.
Full REL Acoustics R-528 review and specifications →
| Amplifier Power | 500W RMS |
|---|---|
| CEA-2010-A Average (40-80Hz) | 112.8 dB (avg of 3/4 bands) |
| Country | United Kingdom |
| Dimensions | 17.5”H x 15.5”W x 17.2”D (444.5 x 393.7 x 436.9 mm) |
| Drivers | 12” (305mm) driver |
| Enclosure | passive radiator |
| Frequency Response | 21Hz-6dB |
| Measurement Source | Brent Butterworth |
| Output SPL at 25 Hz | 92.7 dB |
| Output SPL at 31.5 Hz | 106.5 dB |
| Output SPL at 40 Hz | 111.0 dB |
| Output SPL at 50 Hz | 112.7 dB |
| Output SPL at 63 Hz | 114.6 dB |
| Warranty | 3 |
| Weight | 58 lbs (26.3 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by Brent Butterworth; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons