Short answer: the AsciLab C6B. It ranks #6 of 203 bookshelf speakers by sound quality (rated 4.7/5) at $1,145 and is still sold new; the KEF Q350 ranks #171 (rated 3.0/5) and is discontinued, so it is only an option used. The KEF Q350’s replacement, the KEF Q3 Meta, is rated 3.4/5.
Why pick the KEF Q350: CEA2034 spinorama shows a reasonably flat on-axis response with excellent directivity, aided by the coaxial Uni-Q driver. The catch: Two resonances at 700Hz and 1.2kHz show up on-axis, alongside an upper-bass boost.
The AsciLab C6B is the more accurate, deeper-bass pick. Two-way design pairing a 1” aluminum ceramic dome tweeter on a large waveguide with a 6” aluminum ceramic cone woofer, crossed over at 1.1kHz, plus a rear passive radiator. Its measured preference score, a predictor of how neutral it sounds, is 6.33 against 5.25 for the KEF Q350. Its bass reaches about 54Hz before falling 3dB, against 70Hz for the KEF Q350. The tradeoff: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that.
Buy the AsciLab C6B. It is rated higher for sound quality, and the KEF Q350 is discontinued, so it is only available used.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| KEF Q350 | AsciLab C6B | |
|---|---|---|
| Price | $699.00 per pair Discontinued | $1145 per pair |
| Ranked | #171 of 203 in Large Size Bookshelf Speakers | #6 of 203 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 38Hz (measured, Audio Science Review) | 35Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 70Hz (measured, Audio Science Review) | 54Hz (measured, Erin’s Audio Corner) |
| Impedance | 4 ohms | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 86dB (measured, Audio Science Review) | 85.6dB (measured, Erin’s Audio Corner) |
| Drivers | 25mm tweeter + 165mm woofer | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter |
| Weight | 29.5 lbs (13.4 kg) | 18.5 lbs (8.4 kg) each |
| Dimensions | 14.1”H x 8.3”W x 12”D (358.0 x 210.0 x 306.0 mm) | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) |
| Woofer Cabinet | ported, rear | passive radiator |
| Spinorama Preference Score | 5.25 (spinorama.org) | 6.33 |
| Spinorama Preference Score with Perfect Sub | 7.12 (spinorama.org) | 8.28 |
| DIY Kit | No | No |
Related Speaker Comparisons
More top alternatives to AsciLab C6B:
- AsciLab C6B vs Perlisten S4b
- AsciLab C6B vs KEF Reference 1 Meta
- AsciLab C6B vs GR-Research NX-Studio
- AsciLab C6B vs March Audio Sointuva AWG
- AsciLab C6B vs Audio First Cadentia 3
Prices on this page were last checked October 9, 2026 at 8:01 AM 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 Q350: $699.00 per pair Discontinued Amazon eBay
Newer model: the KEF Q3 Meta, ranked higher, rated 3.4/5.
Same family: the KEF Q150 (smaller bookshelf, rated 3.7/5), the KEF Q250c (smaller center, rated 3.9/5) and the KEF Q650c (larger center, rated 3.7/5).
Pros: CEA2034 spinorama shows a reasonably flat on-axis response with excellent directivity, aided by the coaxial Uni-Q driver. Vertical directivity is better than most non-coaxial two-way speakers, another benefit of the concentric design. Measured bass extension of 70Hz (-3dB), with a measured sensitivity of 86dB.
Cons: Two resonances at 700Hz and 1.2kHz show up on-axis, alongside an upper-bass boost. Predicted in-room response looks a bit boomy as a result. Distortion climbs substantially in the 100Hz-1kHz range at 96dB SPL/1m, with a distinct resonance-driven peak around 900Hz-1kHz at both test levels. Discontinued.
Full KEF Q350 review and specifications →
| Bass Extension (-10dB) | 38Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 70Hz (measured, Audio Science Review) |
| DIY Kit | No |
| Dimensions | 14.1”H x 8.3”W x 12”D (358.0 x 210.0 x 306.0 mm) |
| Drivers | 25mm tweeter + 165mm woofer |
| Impedance | 4 ohms |
| Sensitivity | 86dB (measured, Audio Science Review) |
| Spinorama Preference Score | 5.25 (spinorama.org) |
| Spinorama Preference Score with Perfect Sub | 7.12 (spinorama.org) |
| Weight | 29.5 lbs (13.4 kg) |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
AsciLab C6B: $1145 per pair Ascilab eBay
Same family: the AsciLab C5B (smaller bookshelf, rated 4.2/5).
Pros: Two-way design pairing a 1” aluminum ceramic dome tweeter on a large waveguide with a 6” aluminum ceramic cone woofer, crossed over at 1.1kHz, plus a rear passive radiator. Unusual trait: horizontal radiation actually widens at higher frequencies instead of narrowing like most two-way designs, which keeps image focus and soundstage depth consistent whether you toe the speakers in or out (5-10° off-axis was the sweet spot in testing). Vertical radiation also stays wide straight through the 2kHz crossover region, so the sound doesn’t collapse when standing up: unusual at this price. CA2034 measurements show strong on-axis linearity, listening window, early reflections, and directivity. Midrange and tweeter distortion stay very low even at 96dB, holding up against a $5,900 Arendal speaker in that regard despite roughly a 5x price gap. At $1145 shipped to the US, the reviewer calls it the best-value bookshelf speaker he’s tested, rivaling speakers 2-5x the price. Measured bass extension of 54Hz (-3dB), with a measured sensitivity of 85.6dB.
Cons: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that. Low-frequency harmonic distortion increases substantially at 96dB versus 86dB, though it’s second-order and less audible than it looks on paper. Minimum impedance dips to 2.6 ohms (EPDR as low as 1.2 ohms), so it wants an amplifier comfortable driving 4-ohm loads, ideally 100W or more. At 102dB, compression noticeably eats into midrange, bass, and some treble output. Shipping to the US adds roughly $200 on top of AsciLab’s list price. Against the reviewer’s reference Audiofirst Fidelia at a similar price, has slightly less lower-midrange body (about 1dB difference) and a smaller perceived soundstage size.
Full AsciLab C6B review and specifications →
| Bass Extension (-10dB) | 35Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 54Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) |
| Drivers | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter |
| Impedance | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 85.6dB (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 6.33 |
| Spinorama Preference Score with Perfect Sub | 8.28 |
| Weight | 18.5 lbs (8.4 kg) each |
| Woofer Cabinet | passive radiator |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons