Short answer: the KEF Q Concerto Meta. It ranks #11 of 222 bookshelf speakers by sound quality, rated 4.6/5, at $999.99; the Theory Audio sb25 ranks #120, rated 3.7/5, and costs $3,400, so there is little reason to consider the other one.
The KEF Q Concerto Meta is the more accurate, deeper-bass choice. A neutral three way bookshelf speaker that sounds consistent from seat to seat, with smooth treble that many rivals at its price lack. Its measured preference score, a predictor of how neutral it sounds, is 6.01 against 4.33 for the Theory Audio sb25. Its bass reaches about 53Hz before falling 3dB, against 67.4Hz for the Theory Audio sb25. The catch: Radiation pattern measures about ±50°, narrower than the reviewer’s preferred ±60° for a stronger sense of envelopment.
The case for the Theory Audio sb25: Very slim surface-mount speakers with dual 5 inch woofers, wide dispersion and high output, made for custom installs. The catch: It requires a Theory controller-amplifier channel and model-specific DSP, making it much less straightforward than a normal passive speaker.
Buy the KEF Q Concerto Meta. It is rated higher for sound quality than the Theory Audio sb25 and costs less, so only choose the other one for a particular feature it does better.
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Measured Differences
- Bass depth: the KEF Q Concerto Meta reaches 53 Hz (3 dB down) against 67.4 Hz for the Theory Audio sb25, about half an octave deeper. You hear more of the lowest bass notes and kick drums.
- Tonal accuracy above the bass: with a subwoofer taking the low end, the KEF Q Concerto Meta scores 7.7 against 7.0 for the Theory Audio sb25 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 Theory Audio sb25 is rated at 94 dB sensitivity against 84.2 dB for the KEF Q Concerto Meta, so it plays as loud with roughly a third of the amplifier power.
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Specifications Side By Side
| KEF Q Concerto Meta | Theory Audio sb25 | |
|---|---|---|
| Price | $999.99 per pair | $3,400 per pair |
| Ranked | #11 of 222 in Large Size Bookshelf Speakers | #120 of 222 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 35Hz (measured, Erin’s Audio Corner) | 46Hz (manufacturer specified) |
| Bass Extension (-3dB) | 53Hz (measured, Erin’s Audio Corner) | 67.4Hz (measured, spinorama.org) |
| Dimensions | 16.3”H x 8.3”W x 12.4”D (414 x 210.8 x 315 mm) | 21.5H x 9.5W x 3.8D in |
| Impedance | 4 ohms nominal (3.3 ohms minimum above 80Hz, measured by Erin’s Audio Corner) | 4 ohms |
| Drivers | 165 mm (6.5 in.) hybrid aluminium cone woofer, 100 mm (4 in.) aluminium cone midrange, 19 mm (0.75 in.) vented aluminium dome with MAT tweeter | Dual 5-inch carbon-fiber woofers, 1.4-inch compression driver |
| Sensitivity | 84.2dB (measured average, Erin’s Audio Corner) | 94dB (manufacturer specified, 2.83V/1m) |
| Weight | 20.9 lbs (9.5 kg) each | 22.9 lbs (10.4 kg) each |
| Woofer Cabinet | ported, rear | - |
| Spinorama Preference Score | 6.01 | 4.33 |
| Spinorama Preference Score with Perfect Sub | 7.71 | 6.99 |
| DIY Kit | No | No |
| Enclosure | - | Passive sealed surface/tabletop speaker |
| Frequency Response | - | 54Hz-23kHz (-6dB) |
| Coverage | - | 125 degrees conical |
| Power Handling | - | 200W AES, 800W peak |
| Maximum SPL | - | 123dB peak at 1m |
Where the Ratings Come From
- KEF Q Concerto Meta: Spinorama.org measurements and reviews by Erin’s Audio Corner.
- Theory Audio sb25: Spinorama.org measurements.
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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