REL Acoustics S/850 vs REL Acoustics S/550

Short answer: the REL Acoustics S/850. It ranks #110 of 212 subwoofers by sound quality, rated 3.7/5, at $3,999. The REL Acoustics S/550 ranks #155, rated 3.5/5, at $3,299, $700 cheaper, not enough of a saving to outweigh the sound-quality gap.

What the REL Acoustics S/850 does well: Front-firing 12 inch carbon and aluminum driver plus a down-firing 12 inch passive radiator, driven by an 850W RMS Class D amplifier (1,000W peak). The catch: No independent measurements yet, so its output can’t be compared with ranked subwoofers; the rating is estimated from the measured REL Acoustics R-528, an older 12 inch REL that averaged 112.8dB in the CEA-2010 bands but fell to 92.7dB at 25Hz.

Why pick the REL Acoustics S/550: The smallest model in REL’s 2025 Serie S, replacing the S/510: a 10” CarbonAlloy active driver and a 12” down-firing passive radiator driven by a 550W Linear Class D amplifier, reaching 19Hz (-6dB). The tradeoff: No independent measurements yet, so its output can’t be compared directly with ranked subwoofers; the rating is estimated from the measured REL Acoustics R-528 (112.8dB in three of the four 40 to 80Hz CEA-2010 bands) and its sibling REL Acoustics S/850.

Buy the REL Acoustics S/850. It is rated higher for sound quality, and the $700 you would save on the REL Acoustics S/550 does not close the gap.

About the ratings: neither speaker has been measured yet, so both ratings are estimated from measured siblings and predecessors (likely ranges: REL Acoustics S/850 3.4 to 4.0; REL Acoustics S/550 3.1 to 3.7). Treat this verdict as provisional.

Looking for alternatives? See the complete Subwoofers rankings.

Specifications Side By Side

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• Sigberg Audio INKOGNITO 12 vs REL Acoustics S/850
• REL Acoustics S/850 vs KEF Reference 8b
• Sigberg Audio INKOGNITO 12 vs REL Acoustics S/550

Prices on this page were last checked October 11, 2026 at 4:59 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

REL Acoustics S/850: $3,999.00 Estimated REL Acoustics eBay

Older model: the REL Acoustics R-528 (ranked higher, rated 3.7/5). See every REL S and Reference Series generation.

Same family: the REL Acoustics S/550 (smaller subwoofer, ranked lower, estimated 3.5/5), the REL Acoustics Carbon Special Black Label (larger subwoofer, estimated 3.9/5) and the REL Acoustics 212 Black Label (larger subwoofer, estimated 4.2/5).

Pros: Front-firing 12 inch carbon and aluminum driver plus a down-firing 12 inch passive radiator, driven by an 850W RMS Class D amplifier (1,000W peak). REL rates it at 19Hz at the -6dB point. High level Speakon, RCA and LFE RCA/XLR inputs, and REL’s Airship wireless option, make it easy to blend with stereo and theater systems.

Cons: No independent measurements yet, so its output can’t be compared with ranked subwoofers; the rating is estimated from the measured REL Acoustics R-528, an older 12 inch REL that averaged 112.8dB in the CEA-2010 bands but fell to 92.7dB at 25Hz. At 42.5 kg it is very heavy, and it costs far more than measured 12 inch subwoofers with more output.

Full REL Acoustics S/850 review and specifications →

Released	Sep 2025 (1 year ago)
Amplifier Power	850W RMS (1,000W peak)
Cabinet Color	black, white
Country	United Kingdom
Dimensions	16.1”H x 19.2”W x 21.3”D (410 x 488 x 540 mm)
Drivers	12” (305mm) driver, 12” passive radiator
Enclosure	passive radiator
Frequency Response	19Hz (-6dB, manufacturer specified)
Warranty	3
Weight	93.7 lbs (42.5 kg)

• Links
  • REL Acoustics S/850 Website
• Reviews, Comparisons and Sound Samples
  • No independent measurement review is linked for this model; it is ranked from hands-on listening and comparison against similarly priced speakers.
• Head-to-Head Comparisons
  • REL Acoustics S/850 vs Sigberg Audio INKOGNITO 12
  • REL Acoustics S/850 vs KEF Reference 8b
  • REL Acoustics S/850 vs Sigberg Audio 10D
  • REL Acoustics S/850 vs Paradigm XR11

REL Acoustics S/550: $3,299.00 Estimated Audio Advice eBay

Same family: the REL Acoustics S/850 (larger subwoofer, ranked higher, estimated 3.7/5), the REL Acoustics Carbon Special Black Label (larger subwoofer, estimated 3.9/5) and the REL Acoustics 212 Black Label (larger subwoofer, estimated 4.2/5). See every REL S and Reference Series generation.

Pros: The smallest model in REL’s 2025 Serie S, replacing the S/510: a 10” CarbonAlloy active driver and a 12” down-firing passive radiator driven by a 550W Linear Class D amplifier, reaching 19Hz (-6dB). It includes REL’s high-level speaker connection for integrating with stereo amplifiers.

Cons: No independent measurements yet, so its output can’t be compared directly with ranked subwoofers; the rating is estimated from the measured REL Acoustics R-528 (112.8dB in three of the four 40 to 80Hz CEA-2010 bands) and its sibling REL Acoustics S/850. It is placed below the larger REL Acoustics S/850, and at 31.7kg it is heavy for a 10” sub.

Full REL Acoustics S/550 review and specifications →

Released	Oct 2025 (1 year ago)
Amplifier Power	550W Linear Class D
Country	United Kingdom
Dimensions	16.1”H x 15.7”W x 18.3”D (410 x 400 x 464 mm)
Drivers	10” CarbonAlloy driver, 12” down-firing passive radiator
Enclosure	passive radiator
Frequency Response	19Hz -6dB (manufacturer specified)
Warranty	3
Weight	69.9 lbs (31.7 kg)

• Reviews, Comparisons and Sound Samples
  • No independent measurement review is linked for this model; it is ranked from hands-on listening and comparison against similarly priced speakers.
• Head-to-Head Comparisons
  • REL Acoustics S/550 vs KEF Reference 8b
  • REL Acoustics S/550 vs Genelec 7360A
  • REL Acoustics S/550 vs Sigberg Audio INKOGNITO 12