Short answer: the DIYSG HTM-12 v2. It ranks #14 of 131 bookshelf speakers by sound quality (rated 4.5/5); the Buchardt Audio S400 ranks #29 (rated 4.4/5).
The case for the DIYSG HTM-12 v2: Purpose-built high-output cinema kit pairing a 12-inch woofer with a compression driver in a large SEOS waveguide. The tradeoff: Erin measured F3 at approximately 67Hz, the normal efficiency/bass-extension tradeoff of a high-sensitivity 12-inch design, so a subwoofer is mandatory.
What the Buchardt Audio S400 does well: Compact passive design with a 6-inch aluminum woofer, rear passive radiator and waveguided 0.74-inch tweeter positioned below the woofer. Watch for: The impedance reaches 3.7 ohms (Erin), so a genuinely four-ohm-stable separate amplifier is recommended rather than a basic AVR.
One note: the DIYSG HTM-12 v2 is discontinued, but it still ranks #14 of 131 bookshelf speakers by sound quality, ahead of most of what is still sold new, so it is worth considering used.
Buy the DIYSG HTM-12 v2. It is rated higher for sound quality than the Buchardt Audio S400.
Still deciding? The full Passive Home rankings cover every ranked option.
Specifications Side By Side
| DIYSG HTM-12 v2 | Buchardt Audio S400 | |
|---|---|---|
| Price | $920 per pair per kit, Discontinued | €1,800 per pair Discontinued |
| Ranked | #14 of 131 in Large Size Bookshelf Speakers | #29 of 131 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 45Hz (measured, Erin’s Audio Corner) | 38Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 67Hz (measured, Erin’s Audio Corner) | 53Hz (measured, Erin’s Audio Corner) |
| Sensitivity | 91dB/2.83V/1m (measured, Erin’s Audio Corner) | Approximately 86dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Impedance | AVR-compatible impedance profile (measured, Erin’s Audio Corner) | 3.7 ohms minimum (measured, Erin’s Audio Corner) |
| Drivers | 12” woofer; compression driver in SEOS waveguide | 0.74” waveguided tweeter; 6” aluminum woofer |
| Woofer Cabinet | ported | sealed with rear passive radiator |
| Spinorama Preference Score | 3.26 | 5.23 |
| Spinorama Preference Score with Perfect Sub | 5.88 | 7.43 |
| Dimensions | 25”H x 18”W x 9.5”D (635 x 457.2 x 241.3 mm) | 14.8”H x 7.1”W x 9.6”D (375 x 180 x 245 mm) |
| Weight | 39.9 lbs (18.1 kg) assembled | 16.1 lbs (7.30 kg) each |
| DIY Kit | Yes | No |
Related Speaker Comparisons
More worthwhile head-to-heads for DIYSG HTM-12 v2:
- AsciLab F6B vs DIYSG HTM-12 v2
- ELAC Debut 3.0 DB63 vs DIYSG HTM-12 v2
- Klipsch RP-600M II vs DIYSG HTM-12 v2
- DIYSG HTM-12 v2 vs Fosi Audio SP601
- TAD Compact Reference One (CR1TX) vs Buchardt Audio S400
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
DIYSG HTM-12 v2: $920 per pair per kit Discontinued DIY Sound Group eBay
Pros: Purpose-built high-output cinema kit pairing a 12-inch woofer with a compression driver in a large SEOS waveguide. Erin measured 91dB/2.83V/1m sensitivity, extraordinarily low distortion (still below 1% to about 60Hz at 102dB) and only about 0.5dB tweeter compression at the same level. Horizontal directivity is consistent and crossover integration is unusually good, so response corrections remain EQ-friendly. The benign impedance curve can be driven by many capable AVRs. Measured bass extension of 67Hz (-3dB), with a measured sensitivity of 91dB.
Cons: Erin measured F3 at approximately 67Hz, the normal efficiency/bass-extension tradeoff of a high-sensitivity 12-inch design, so a subwoofer is mandatory. A few narrow resonances appear in the response, impedance and decay plots; Erin suggested crossover/component investigation could improve them. Vertical radiation narrows around the crossover, the unfinished kit requires cabinet assembly and finishing, and its broad baffle is visually and physically substantial. Discontinued.
Full DIYSG HTM-12 v2 review and specifications →
| Bass Extension (-10dB) | 45Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 67Hz (measured, Erin’s Audio Corner) |
| DIY Kit | Yes |
| Dimensions | 25”H x 18”W x 9.5”D (635 x 457.2 x 241.3 mm) |
| Drivers | 12” woofer; compression driver in SEOS waveguide |
| Impedance | AVR-compatible impedance profile (measured, Erin’s Audio Corner) |
| Sensitivity | 91dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 3.26 |
| Spinorama Preference Score with Perfect Sub | 5.88 |
| Weight | 39.9 lbs (18.1 kg) assembled |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Buchardt Audio S400: €1,800 per pair Discontinued eBay
Newer model: the Buchardt S400 MK3. It’s likely to perform similarly, though we can’t confirm that yet.
Pros: Compact passive design with a 6-inch aluminum woofer, rear passive radiator and waveguided 0.74-inch tweeter positioned below the woofer. Erin measured F3/F10 at 53Hz/38Hz, approximately 86dB/2.83V/1m sensitivity and smooth, broad horizontal directivity. The waveguide controls crossover handoff effectively, the passive radiator avoids port chuffing, and Erin heard no objectionable narrow-band distortion despite excellent extension for the enclosure volume. Measured bass extension of 53Hz (-3dB), with a measured sensitivity of 86dB.
Cons: The impedance reaches 3.7 ohms (Erin), so a genuinely four-ohm-stable separate amplifier is recommended rather than a basic AVR. Low-frequency distortion naturally rises at high output and the compact woofer cannot supply theater-level deep bass; crossing to a subwoofer protects headroom. Erin measured narrow distortion features above 8-9kHz and vertical lobing outside the intended axis. This is the original S400, distinct from the S400 MKII already ranked. Discontinued.
Full Buchardt Audio S400 review and specifications →
| Bass Extension (-10dB) | 38Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 53Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 14.8”H x 7.1”W x 9.6”D (375 x 180 x 245 mm) |
| Drivers | 0.74” waveguided tweeter; 6” aluminum woofer |
| Impedance | 3.7 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | Approximately 86dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 5.23 |
| Spinorama Preference Score with Perfect Sub | 7.43 |
| Weight | 16.1 lbs (7.30 kg) each |
| Woofer Cabinet | sealed with rear passive radiator |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons