Short answer: the Sony SS-CS5 M2 for a smoother cabinet, the KEF Q150 for imaging. Added internal bracing and an updated crossover meaningfully reduce the resonance issues of the original SS-CS5, giving the M2 a more neutral character; its remaining flaw is mild sibilance in the 3-5kHz range. The Q150’s Uni-Q time-aligns its 1” dome and 5.25” mid, but a high-frequency lift brightens untreated rooms.
Buy the Sony SS-CS5 M2 if you want one new; the KEF Q150 is discontinued, so only look for it used.
Still deciding? The full Passive Home rankings cover every ranked option.
Specifications Side By Side
| KEF Q150 | Sony SS-CS5 M2 | |
|---|---|---|
| Price | $350 per pair Discontinued | $278.00 per pair |
| Ranked | #26 of 90 in Medium Size Bookshelf Speakers | #49 of 90 in Medium Size Bookshelf Speakers |
| Bass Extension (-10dB) | 44Hz (measured, Erin’s Audio Corner) | 54Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) | 80Hz (measured, Erin’s Audio Corner) |
| Dimensions | 11.9”H x 7.1”W x 10.9”D (303 x 180 x 278 mm) | 13.2”H x 7”W x 8.7”D (335 x 178 x 220 mm) |
| Impedance | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin’s Audio Corner) | 6 ohms |
| Sensitivity | ~85dB (300Hz-3kHz on-axis, measured, Erin’s Audio Corner) | 82.5dB |
| Drivers | 130mm (5.25”) aluminium Uni-Q woofer, 25mm (1”) vented aluminium dome tweeter | 5.12” woofer, 0.98 in tweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter |
| Weight | 12.3 lbs (5.6 kg) each | 9.5 lbs (4.3 kg) each |
| Woofer Cabinet | ported, rear | ported, rear |
| Spinorama Preference Score | 4.86 | - |
| Spinorama Preference Score with Perfect Sub | 7.06 | - |
| DIY Kit | No | No |
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The Two Speakers In Full
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
Sony SS-CS5 M2: $278.00 per pair Amazon eBay
Pros: Added internal bracing (corners, sides, front baffle) plus an updated crossover meaningfully reduce the resonance issues that plagued the original SS-CS5, giving a smoother, more neutral character overall. A modest mid-range dip (about 1-2dB) is present but tolerable, and the reviewer would rather have this dip than a peak in that region. Slightly deeper bass than the previous version, measuring about 2dB more output around 60Hz. Distortion drops noticeably when crossed to a subwoofer around 80-120Hz, meaningfully improving midrange clarity and detail versus running full-range. Easy to drive on a standard AVR: no need for a dedicated high-power amplifier. More modern, understated waveguide look compared to the previous version’s glossy trim. Measured bass extension of 80Hz (-3dB).
Cons: Mild sibilance in the 3-5kHz range stands out on S and T sounds in vocals. Some forwardness in the midrange noticeable on certain vocal recordings. Soundstage and sense of envelopment are comparatively flat and two-dimensional, especially next to reference-quality speakers with strong 3D imaging. Marketed as a “three-way” design mainly due to an added super-tweeter that the reviewer considers largely superfluous: it engages only at very high frequencies and adds complexity without a clearly audible benefit, when that cost might have been better spent on the main crossover. Output-limited: realistic ceiling is around the mid-90s dB SPL at a few meters, with comfortable listening closer to 75-85dB at 3-4 meters before distortion and compression become audible. Bass noticeably compresses/shelves below about 120Hz as volume increases, softening kick-drum impact at higher output. Smaller drivers and a lighter motor structure than rivals like the Polk XT20, which the reviewer generally prefers for its better directivity and higher SPL capability. Still needs a subwoofer for any real bass extension.
Full Sony SS-CS5 M2 review and specifications →
| Bass Extension (-10dB) | 54Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 80Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 13.2”H x 7”W x 8.7”D (335 x 178 x 220 mm) |
| Drivers | 5.12” woofer, 0.98 in tweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter; 0.75-inch supertweeter |
| Impedance | 6 ohms |
| Sensitivity | 82.5dB |
| Weight | 9.5 lbs (4.3 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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