Short answer: the KEF R3 has been measured and ranked among bookshelf speakers; the Buchardt S400 MK3 has not been independently measured yet, so until it is, this comes down to features and price.
What the Buchardt S400 MK3 offers: 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.
What the KEF R3 brings: True three-way stand-mount with a 6.5-inch woofer below KEF’s 5-inch Uni-Q midrange/1-inch tweeter.
Price: the Buchardt S400 MK3 lists at $2,300 and the KEF R3 at $2,200.
Buy the KEF R3 if you want a speaker whose sound quality has been measured and ranked.
Buy the Buchardt S400 MK3 if you prefer its design or features, and you can wait for measurements to confirm how it sounds.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Buchardt S400 MK3 | KEF R3 | |
|---|---|---|
| Price | $2,300 per pair | $2,200 per pair |
| Ranked | - | #15 of 131 in Large Size Bookshelf Speakers |
| Crossover Frequency | 2.2kHz (first order) | - |
| Dimensions | 392H x 198W x 280D mm | 16.6”H x 7.9”W x 13.2”D |
| DIY Kit | No | No |
| Drivers | 1” aluminum dome tweeter in waveguide, 7.5” Satori Papyrus paper cone woofer | 1” tweeter coaxial with 5” midrange; 6.5” woofer |
| Frequency Response | 33Hz - 20kHz (in-room, manufacturer specified) | - |
| Impedance | 4 ohms | 8 ohms nominal; suitable for Erin’s 4/8-ohm-rated amplifier |
| Sensitivity | 87dB anechoic, 90dB in-room (manufacturer specified) | Approximately 86-87dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Weight | 8.5 kg each | 29.9 lbs (13.55 kg) each |
| Woofer Cabinet | ported, rear | ported, rear Flexible Port |
| Bass Extension (-3dB) | - | Approximately 58Hz (manufacturer specified; consistent with Erin’s measured roll-off) |
| Bass Extension (-10dB) | - | 35.2Hz (measured, Audio Science Review) |
| Spinorama Preference Score | - | 6.2 (spinorama.org) |
| Spinorama Preference Score with Perfect Sub | - | 7.97 (spinorama.org) |
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.
As an eBay Partner, we may be compensated if you make a purchase.
The Two Speakers In Full
Buchardt S400 MK3: $2,300 per pair Buchardt Audio eBay
Older models: the Buchardt Audio S400 (rated 4.4/5) and the Buchardt S400 MKII (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 | 392H x 198W x 280D 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 | 8.5 kg each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- These figures are manufacturer-specified rather than independently measured.
- Head-to-Head Comparisons
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