Short answer: the Ascend Acoustics Sierra 1 v2. It ranks #3 of 179 bookshelf speakers by sound quality (rated 4.7/5) at $1,000 and is still sold new; the KEF Q150 ranks #48 (rated 3.7/5) and is discontinued, so it is only an option used. The KEF Q150’s replacement, the KEF Q1 Meta, is rated 3.6/5 at $399.99.
The Ascend Acoustics Sierra 1 v2 is the more accurate choice. An extremely accurate bookshelf speaker, with a bamboo cabinet, wide even dispersion and clean output when played loud. Its measured preference score, a predictor of how neutral it sounds, is 6.65 against 4.86 for the KEF Q150. The tradeoff: 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: Compact bookshelf speakers with a tweeter set in the center of the woofer, usable ported or sealed and easy to correct with EQ. 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.
Buy the Ascend Acoustics Sierra 1 v2. It is rated higher for sound quality, and the KEF Q150 is discontinued, so it is only available used.
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Measured Differences
- Tonal accuracy above the bass: with a subwoofer taking the low end, the Ascend Acoustics Sierra 1 v2 scores 8.6 against 7.1 for the KEF Q150 on the Spinorama preference scale. Its frequency response and off-axis sound are smoother, so voices and instruments sound closer to the recording.
- Efficiency: the KEF Q150 is rated at 85 dB sensitivity against 81.5 dB for the Ascend Acoustics Sierra 1 v2, so it plays as loud with roughly half the amplifier power.
- Close enough not to matter: bass extension (39 Hz vs 44 Hz, 10 dB down).
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Specifications Side By Side
| Ascend Acoustics Sierra 1 v2 | KEF Q150 | |
|---|---|---|
| Price | $1000 per pair | $350 per pair Discontinued |
| Ranked | #3 of 179 in Medium Size Bookshelf Speakers | #48 of 179 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 |
Watch Them Compared
Videos and reviews that test both speakers side by side.
Where the Ratings Come From
- Ascend Acoustics Sierra 1 v2: Spinorama.org measurements and reviews by Erin’s Audio Corner and Audio Science Review Ascend.
- KEF Q150: Spinorama.org measurements and reviews by Erin’s Audio Corner and GR-Research.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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