Short answer: the KEF R3. It ranks #15 of 141 bookshelf speakers by sound quality, rated 4.5/5, at $2,200; the Buchardt S400 MK3 ranks #59, rated 4.0/5, and costs $2,300, which makes this an easy call rather than a real tradeoff.
The KEF R3 is the better-sounding choice. True three-way stand-mount with a 6.5-inch woofer below KEF’s 5-inch Uni-Q midrange/1-inch tweeter. The catch: The low-frequency alignment rolls gradually rather than delivering high-output sub-bass; KEF specifies 58Hz +/-3dB and Erin’s high-level data supports using an 80Hz subwoofer crossover.
The case for the Buchardt S400 MK3: A ground-up redesign of the S400 with an 18 percent larger cabinet and a 7.5” SB Acoustics Satori Papyrus paper cone woofer, which Buchardt says has 65.5 percent more displacement than the MKII’s 6” driver. The catch: No independent measurements have been published yet.
Buy the KEF R3. It is rated higher for sound quality than the Buchardt S400 MK3 and costs less, so only choose the other one for a particular feature it does better.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| KEF R3 | Buchardt S400 MK3 | |
|---|---|---|
| Price | $2,200 per pair | $2,300 per pair |
| Ranked | #15 of 141 in Large Size Bookshelf Speakers | #59 of 141 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | Approximately 58Hz (manufacturer specified; consistent with Erin’s measured roll-off) | - |
| Bass Extension (-10dB) | 35.2Hz (measured, Audio Science Review) | - |
| Sensitivity | Approximately 86-87dB/2.83V/1m (measured, Erin’s Audio Corner) | 87dB anechoic, 90dB in-room (manufacturer specified) |
| Impedance | 8 ohms nominal; suitable for Erin’s 4/8-ohm-rated amplifier | 4 ohms |
| Drivers | 1” tweeter coaxial with 5” midrange; 6.5” woofer | 1” aluminum dome tweeter in waveguide, 7.5” Satori Papyrus paper cone woofer |
| Dimensions | 16.6”H x 7.9”W x 13.2”D | 15.4”H x 7.8”W x 11”D (392 x 198 x 280 mm) |
| Woofer Cabinet | ported, rear Flexible Port | ported, rear |
| Weight | 29.9 lbs (13.55 kg) each | 18.7 lbs (8.5 kg) each |
| Spinorama Preference Score | 6.2 (spinorama.org) | - |
| Spinorama Preference Score with Perfect Sub | 7.97 (spinorama.org) | - |
| DIY Kit | No | No |
| Crossover Frequency | - | 2.2kHz (first order) |
| Frequency Response | - | 33Hz - 20kHz (in-room, manufacturer specified) |
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Prices on this page were last checked October 4, 2026 at 9:58 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 R3: $2,200 per pair Amazon eBay
Pros: True three-way stand-mount with a 6.5-inch woofer below KEF’s 5-inch Uni-Q midrange/1-inch tweeter. Erin measured approximately 86-87dB/2.83V/1m sensitivity, exceptionally low sub-1% distortion at 86dB and orderly directivity in both planes. The coaxial geometry maintains image stability across seats, while Flexible Port Technology avoids the strong midrange port resonance common to rear-vented competitors. A 110W Parasound drove it successfully in Erin’s listening. Measured bass extension of 35.2Hz (-10dB), with a measured sensitivity of 87dB.
Cons: The low-frequency alignment rolls gradually rather than delivering high-output sub-bass; KEF specifies 58Hz +/-3dB and Erin’s high-level data supports using an 80Hz subwoofer crossover. Narrow high-frequency features and natural Uni-Q narrowing toward the top octave make toe angle audible, although off-axis tracking remains smooth. Sensitivity is moderate, the cabinet weighs almost 30 lb, and this original R3 lacks the Meta successor’s MAT absorber.
Full KEF R3 review and specifications →
| Bass Extension (-10dB) | 35.2Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | Approximately 58Hz (manufacturer specified; consistent with Erin’s measured roll-off) |
| DIY Kit | No |
| Dimensions | 16.6”H x 7.9”W x 13.2”D |
| Drivers | 1” tweeter coaxial with 5” midrange; 6.5” woofer |
| Impedance | 8 ohms nominal; suitable for Erin’s 4/8-ohm-rated amplifier |
| Sensitivity | Approximately 86-87dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 6.2 (spinorama.org) |
| Spinorama Preference Score with Perfect Sub | 7.97 (spinorama.org) |
| Weight | 29.9 lbs (13.55 kg) each |
| Woofer Cabinet | ported, rear Flexible Port |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: KEF R3 Review More from Erin’s Audio Corner →
- Erin’s Audio Corner Website: KEF R3
- Audio Science Review Measurements More from Audio Science Review →
- Audio Science Review Measurements (spinorama.org)
- Erin’s Audio Corner: Which is Better for Home Theater: (3) Kef R3 or (3) Kef R2c Center Channel speakers?
- Erin’s Audio Corner: KEF R3 vs R3 Meta vs Reference 1 Meta. Why such a big price gap?
- Head-to-Head Comparisons
Buchardt S400 MK3: $2,300 per pair Estimated Buchardt Audio eBay
Older models: the Buchardt Audio S400 (ranked higher, rated 4.4/5) and the Buchardt S400 MKII (ranked lower, rated 3.8/5).
Pros: A ground-up redesign of the S400 with an 18 percent larger cabinet and a 7.5” SB Acoustics Satori Papyrus paper cone woofer, which Buchardt says has 65.5 percent more displacement than the MKII’s 6” driver. A custom 1” aluminum dome tweeter sits in a new waveguide, crossed at 2.2kHz with a first order Jantzen crossover. Buchardt rates in-room bass extension to 33Hz and anechoic sensitivity at 87dB, and includes foam port plugs to trim bass near a wall. Sold direct with free worldwide shipping, duties included, and a 10 year warranty for the first owner.
Cons: No independent measurements have been published yet. The S400 MKII measured very well, but the MK3 shares only its binding posts, so that result can’t be carried over and its linearity, directivity and real bass extension are unknown. The 33Hz figure is an in-room number, not an anechoic one. The MKII’s adjustable passive radiator is gone in favor of a rear port that wants at least 5cm from the wall. A 4 ohm load means it needs an amplifier comfortable driving 4 ohms, and it is sold only direct from Buchardt.
Full Buchardt S400 MK3 review and specifications →
| Crossover Frequency | 2.2kHz (first order) |
|---|---|
| DIY Kit | No |
| Dimensions | 15.4”H x 7.8”W x 11”D (392 x 198 x 280 mm) |
| Drivers | 1” aluminum dome tweeter in waveguide, 7.5” Satori Papyrus paper cone woofer |
| Frequency Response | 33Hz - 20kHz (in-room, manufacturer specified) |
| Impedance | 4 ohms |
| Sensitivity | 87dB anechoic, 90dB in-room (manufacturer specified) |
| Weight | 18.7 lbs (8.5 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- 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
- Buchardt S400 MK3 vs ELAC DBR62
- Buchardt S400 MK3 vs Buchardt S400 MKII
- Buchardt S400 MK3 vs ELAC Debut 3.0 DB63
- Buchardt S400 MK3 vs Klipsch RP-600M II
- Buchardt S400 MK3 vs Wharfedale Linton 85
- Buchardt S400 MK3 vs Wharfedale Super Linton
- Buchardt S400 MK3 vs KEF Q3 Meta
- Buchardt S400 MK3 vs KEF Q Concerto Meta
- See all 10 comparisons