Short answer: the Ascend Sierra 1 v2. It ranks #3 of 88 bookshelf speakers by sound quality, rated 4.7/5, at $1,000. The KEF Q150 ranks #26, rated 3.7/5, at $350, $650 cheaper, a saving that is not big enough to make up the sound-quality gap.
What the Ascend Sierra 1 v2 does well: Formaldehyde-free layered bamboo ply cabinet with a 1” dome tweeter over a 5.25” midwoofer, mated by a 4th-order acoustic crossover rather than a stock textbook design. The catch: F3 of 55Hz and F10 of 39Hz mean in-room extension tops out in the mid-40s Hz; the reviewer still recommends a subwoofer for full-range material.
The case for the KEF Q150: Two-way coaxial (Uni-Q) design with a 1” dome tweeter and 5.25” mid-range time-aligned in a single driver assembly, available in ported or sealed configuration. The tradeoff: A high-frequency lift in the estimated in-room response makes it sound noticeably brighter in an untreated room than in a heavily acoustically-treated one: a real preference factor depending on your room’s furnishings.
One note: the KEF Q150 is discontinued, but it still ranks #26 of 88 bookshelf speakers by sound quality, ahead of most of what is still sold new, so it is worth considering used.
Buy the Ascend Sierra 1 v2. It is rated higher for sound quality, and the $650 you would save on the KEF Q150 does not close the gap.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Ascend Sierra 1 v2 | KEF Q150 | |
|---|---|---|
| Price | $1000 per pair | $350 per pair Discontinued |
| Ranked | #3 of 88 in Medium Size Bookshelf Speakers | #26 of 88 in Medium Size Bookshelf Speakers |
| Bass Extension (-10dB) | 39Hz (measured, Erin’s Audio Corner) | 44Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 55Hz (measured, Erin’s Audio Corner) | 51Hz (measured, Erin’s Audio Corner) |
| Dimensions | 14.2”H x 7.5”W x 10.5”D (361.9 x 190.5 x 266.7 mm) | 11.9”H x 7.1”W x 10.9”D (303 x 180 x 278 mm) |
| Impedance | 8 ohms nominal, 7 ohms minimum (measured, Erin’s Audio Corner) | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 81.5dB (measured, Erin’s Audio Corner) | ~85dB (300Hz-3kHz on-axis, measured, Erin’s Audio Corner) |
| Drivers | 5.25” proprietary mineral-filled polypropylene cone with cast aluminum frame woofer, 26mm aluminum/magnesium alloy dome tweeter with titanium former (SEAS Titan) | 130mm (5.25”) aluminium Uni-Q woofer, 25mm (1”) vented aluminium dome tweeter |
| Weight | 18.5 lbs (8.4 kg) each | 12.3 lbs (5.6 kg) each |
| Woofer Cabinet | ported | ported, rear |
| Spinorama Preference Score | 6.65 | 4.86 |
| Spinorama Preference Score with Perfect Sub | 8.61 | 7.06 |
| DIY Kit | No | No |
Related Speaker Comparisons
More worthwhile head-to-heads for Ascend Sierra 1 v2:
- Ascend Sierra 1 v2 vs Audio First Fidelia
- Ascend Sierra 1 v2 vs Philharmonic Ceramic Mini
- Ascend Sierra 1 v2 vs KEF LS50 Meta
- Ascend Sierra 1 v2 vs XMechanik Mechano23 DIY
- Ascend Sierra 1 v2 vs Ascend Acoustics HTM-200SE2
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The Two Speakers In Full
Ascend Sierra 1 v2: $1000 per pair Ascend Acoustics eBay
Pros: Formaldehyde-free layered bamboo ply cabinet with a 1” dome tweeter over a 5.25” midwoofer, mated by a 4th-order acoustic crossover rather than a stock textbook design. In-room response is extremely linear (the reviewer called it “textbook”) a clear step up from the earlier V1, which had boxiness around 700Hz-1kHz and sibilance around 4-6kHz. Preference score of 8.4 with a subwoofer (6.8 without), which the reviewer calls topnotch. Wide, even horizontal radiation of about ±70° up to 6kHz. Better vertical directivity than its tweeter-to-woofer spacing would suggest, thanks to the steep 4th-order crossover slopes. No mechanical noise, port chuffing, or woofer bottoming even driven to 96dB/1m. In a three-way comparison against the Dynaudio Emit 20 and a Revel bookshelf model (all around $1,000/pair), measured as the most linear of the three and was the reviewer’s personal pick over both, despite the Dynaudio’s deeper bass and higher output capability. Independent ASR Klippel measurements corroborate Erin’s findings: superb off-axis response with only slight on-axis variations, and an in-room response the reviewer called “incredibly smooth and accurate. Amazing for a non-DSP speaker.” Distortion above 200Hz at 86dB/1m is very low for the class. Measured bass extension of 55Hz (-3dB), with a measured sensitivity of 81.5dB.
Cons: F3 of 55Hz and F10 of 39Hz mean in-room extension tops out in the mid-40s Hz; the reviewer still recommends a subwoofer for full-range material. Diffraction dips appear around 3kHz and 5-6kHz, and the 1” dome tweeter starts beaming above roughly 6.7kHz, narrowing the soundstage radiation in the top octave: a straightforward consequence of dome size rather than a design flaw. At 96dB/1m the 5.25” midwoofer shows increased distortion in the midrange, likely tied to motor topology; high-passing to a subwoofer around 80Hz largely clears it up. Moderate sensitivity (~81-82dB average) with a 7-ohm minimum impedance. ASR’s power-sweep testing found response holds steady up to 96dB SPL/1m, but pushing to 102dB causes midbass below 400Hz to sag with distortion “through the roof”: a harder output ceiling than the 96dB tests alone suggest. Vertical directivity also narrows above about 1kHz, so the reviewer recommends staying at tweeter-axis height for best results.
Full Ascend Sierra 1 v2 review and specifications →
| Bass Extension (-10dB) | 39Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 55Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 14.2”H x 7.5”W x 10.5”D (361.9 x 190.5 x 266.7 mm) |
| Drivers | 5.25” proprietary mineral-filled polypropylene cone with cast aluminum frame woofer, 26mm aluminum/magnesium alloy dome tweeter with titanium former (SEAS Titan) |
| Impedance | 8 ohms nominal, 7 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 81.5dB (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 6.65 |
| Spinorama Preference Score with Perfect Sub | 8.61 |
| Weight | 18.5 lbs (8.4 kg) each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: NEW! Ascend Acoustics Sierra-1 V2 Review More from Erin’s Audio Corner →
- Erin’s Audio Corner Website Ascend Sierra 1 v2
- Audio Science Review Ascend Sierra 1 v2 More from Audio Science Review →
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner: I Tested 250 Speakers So You Don’t Have To!
- Erin’s Audio Corner: My Top Picks of 2023: Must-Haves Under $3000
- Manufacturer Measurements (spinorama.org)
- Head-to-Head Comparisons
- Ascend Sierra 1 v2 vs KEF LS50 Meta
- Ascend Sierra 1 v2 vs Philharmonic Ceramic Mini
- Ascend Sierra 1 v2 vs Audio First Fidelia
- Ascend Sierra 1 v2 vs XMechanik Mechano23 DIY
- Ascend Sierra 1 v2 vs Ascend Acoustics HTM-200SE2
- Ascend Sierra 1 v2 vs Arendal 1961 Monitor
- Ascend Sierra 1 v2 vs Ascend Acoustics Luna V2 Mini-Monitor Titan
- Ascend Sierra 1 v2 vs Aalto Speakers Aalto 1 EVO
- See all 49 comparisons
KEF Q150: $350 per pair Discontinued Amazon eBay
Newer model: the KEF Q1 Meta, ranked lower, rated 3.6/5.
Pros: Two-way coaxial (Uni-Q) design with a 1” dome tweeter and 5.25” mid-range time-aligned in a single driver assembly, available in ported or sealed configuration. Exceptional soundstage depth, a hallmark of KEF’s coaxial designs that the reviewer says few other speakers match. Bass extension reaches into kick-drum territory, respectable for a compact bookshelf speaker. Resonances present in measurements are consistent across on- and off-axis readings, meaning they can be effectively corrected with EQ. Distortion profile is essentially the same whether run sealed or ported, since a subwoofer crossover point sits above where the differences would matter anyway. At its sale price (around $300, sometimes seen at $400), the reviewer considers it a clear step up from his previous budget favorite in this range, the Emotiva B1+, mainly due to the superior soundstage depth. Measured bass extension of 51Hz (-3dB), with a measured sensitivity of 85dB.
Cons: A high-frequency lift in the estimated in-room response makes it sound noticeably brighter in an untreated room than in a heavily acoustically-treated one: a real preference factor depending on your room’s furnishings. A mild dip in the 1-2kHz region reduces vocal fullness somewhat. Unexplained resonances appear in measurements and persist in both sealed and ported configurations, pointing to enclosure or panel vibration rather than the port. Horizontal radiation is narrower than the reviewer generally prefers from KEF’s lineup, with directivity that widens somewhat around 1.2kHz (near a resonance) and again above about 5kHz. Compression testing at high output (102dB) shows significant nonlinearity, especially at lower frequencies: noticeably worse than a comparable Arendal bookshelf speaker costing over twice as much, which held up better until 80Hz. Not intended for loud listening without a subwoofer: the woofer will over-exert itself without a high-pass filter, and the reviewer recommends crossing over at 80-120Hz. At full retail price (around $600/pair), the value proposition is far less certain than at sale pricing. Discontinued.
Full KEF Q150 review and specifications →
| Bass Extension (-10dB) | 44Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 11.9”H x 7.1”W x 10.9”D (303 x 180 x 278 mm) |
| Drivers | 130mm (5.25”) aluminium Uni-Q woofer, 25mm (1”) vented aluminium dome tweeter |
| Impedance | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | ~85dB (300Hz-3kHz on-axis, measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 4.86 |
| Spinorama Preference Score with Perfect Sub | 7.06 |
| Weight | 12.3 lbs (5.6 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: Kef’s Cheapest Bookshelf. Is the Q150 worth your money? More from Erin’s Audio Corner →
- Erin’s Audio Corner Website KEF Q150
- GR-Research: KEF Q150… can it get any BETTER? More from GR-Research →
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner: Budget Stereo Systems You Will Love
- Erin’s Audio Corner Measurements (spinorama.org)
- Head-to-Head Comparisons