Short answer: the KEF R3. It ranks #15 of 131 bookshelf speakers by sound quality, rated 4.5/5, at $2,200; the Buchardt S400 MKII ranks #64, rated 3.8/5, and costs $2,400, so there is little reason to consider the other one.
The case for the KEF R3: True three-way stand-mount with a 6.5-inch woofer below KEF’s 5-inch Uni-Q midrange/1-inch tweeter. Watch for: 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.
Why pick the Buchardt S400 MKII: Two-way design with a 3/4” tweeter on a well-implemented aluminum waveguide (compression-driver style, letting the small tweeter cross unusually low at 1800Hz), a 6” SB Acoustics-style mid-woofer, and a tunable 5x8” passive radiator adjustable via rear weights. The tradeoff: Sounds a bit bright and slightly boosted above about 7-8kHz on-axis, even with 30° of toe-out - benefits from about 1 inch of sidewall absorption at the first reflection points to tame it.
Buy the KEF R3. It is rated higher for sound quality than the Buchardt S400 MKII and costs less, which makes it the one to get unless you need something the other one does better.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| KEF R3 | Buchardt S400 MKII | |
|---|---|---|
| Price | $2,200 per pair | $2400 per pair |
| Ranked | #15 of 131 in Large Size Bookshelf Speakers | #64 of 131 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | Approximately 58Hz (manufacturer specified; consistent with Erin’s measured roll-off) | 59Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 35.2Hz (measured, Audio Science Review) | 40Hz (measured, Erin’s Audio Corner) |
| Sensitivity | Approximately 86-87dB/2.83V/1m (measured, Erin’s Audio Corner) | 84.7dB (measured, Erin’s Audio Corner; 87dB manufacturer specified) |
| Impedance | 8 ohms nominal; suitable for Erin’s 4/8-ohm-rated amplifier | 4 ohms nominal, 3 ohms minimum (measured, Erin’s Audio Corner) |
| Drivers | 1” tweeter coaxial with 5” midrange; 6.5” woofer | 6.5” aluminum cone woofer, 1” soft dome tweeter |
| Dimensions | 16.6”H x 7.9”W x 13.2”D | 14.4”H x 7”W x 11”D (365.8 x 177.8 x 279.4 mm) |
| Woofer Cabinet | ported, rear Flexible Port | ported |
| Weight | 29.9 lbs (13.55 kg) each | 16.5 lbs (7.5 kg) each |
| Spinorama Preference Score | 6.2 (spinorama.org) | 5.38 |
| Spinorama Preference Score with Perfect Sub | 7.97 (spinorama.org) | 7.46 |
| DIY Kit | No | No |
Related Speaker Comparisons
How KEF R3 compares with other leading options:
- KEF R3 vs Perlisten S4b
- KEF Reference 1 Meta vs KEF R3
- KEF R3 vs GR-Research NX-Studio
- AsciLab C6B vs KEF R3
- KEF R3 vs Audio First Cadentia 3
Prices on this page were last checked September 26, 2026 at 11:14 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
- Head-to-Head Comparisons
Buchardt S400 MKII: $2400 per pair Buchardt Audio eBay
Older model: the Buchardt Audio S400 (rated 4.4/5).
Pros: Two-way design with a 3/4” tweeter on a well-implemented aluminum waveguide (compression-driver style, letting the small tweeter cross unusually low at 1800Hz), a 6” SB Acoustics-style mid-woofer, and a tunable 5x8” passive radiator adjustable via rear weights. Exceptionally flat on-axis linearity, within about ±2dB from 80Hz to 16kHz. Wide horizontal radiation for a waveguided design (about ±45-50°), notably broader than a comparable narrow-waveguide rival like the Klipsch Sevens (~±30°). Well-focused, precise imaging, aided by tight pair matching between the two speakers. Takes very well to EQ correction, letting listeners easily dial in the top end or add midrange fullness to taste. Bass extension reaches a genuine 50Hz in-room from a mellow, well-tuned rolloff rather than an artificially boosted one. Measured bass extension of 59Hz (-3dB), with a measured sensitivity of 84.7dB.
Cons: Sounds a bit bright and slightly boosted above about 7-8kHz on-axis, even with 30° of toe-out - benefits from about 1 inch of sidewall absorption at the first reflection points to tame it. A mild dullness noted especially on male vocals, alongside a small dip around 300-600Hz. Vertical positioning is critical and unusually “temperamental” - sitting even slightly toward the tweeter line causes a suckout, while sitting above it adds too much energy; not well suited to multi-height home theater seating. Distortion is fine at 86dB but runs into real issues by 96dB - not a high-output speaker. Some compression-related enhancement appears around 1.2kHz (crossover-region interaction), and the tweeter shows clear compression at 102dB. The woofer can bottom out at extreme low-frequency content played very loud; crossing to a subwoofer below 60Hz caused output problems at high volume, while 80-100Hz worked well. A subwoofer isn’t strictly required to protect the speaker at moderate listening levels (80-85dB at 3 meters), but is still recommended for genuine low-octave extension.
Full Buchardt S400 MKII review and specifications →
| Bass Extension (-10dB) | 40Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 59Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 14.4”H x 7”W x 11”D (365.8 x 177.8 x 279.4 mm) |
| Drivers | 6.5” aluminum cone woofer, 1” soft dome tweeter |
| Impedance | 4 ohms nominal, 3 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 84.7dB (measured, Erin’s Audio Corner; 87dB manufacturer specified) |
| Spinorama Preference Score | 5.38 |
| Spinorama Preference Score with Perfect Sub | 7.46 |
| Weight | 16.5 lbs (7.5 kg) each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Buchardt S400 MKII vs Klipsch RP-600M II
- Buchardt S400 MKII vs ELAC DBR62
- Buchardt S400 MKII vs Dynaudio Emit 20
- Buchardt S400 MKII vs Philharmonic BMR Monitor
- Buchardt S400 MKII vs Dynaudio Special Forty
- Buchardt S400 MKII vs ELAC Debut 3.0 DB63
- Buchardt S400 MKII vs KEF Q3 Meta
- Buchardt S400 MKII vs Sonus Faber Lumina II
- See all 17 comparisons