Short answer: the KEF Q150. It ranks #14 of 34 bookshelf speakers by sound quality at $350; the Acoustic Energy AE100 Mk2 ranks #23 and costs $500, so there is not much of a tradeoff to weigh.
What the KEF Q150 offers: 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. Watch for: 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.
What the Acoustic Energy AE100 Mk2 offers: Good directivity linearity - on-axis and off-axis response track each other well despite an otherwise uneven overall response, which means the tonal problems can be EQ’d out with reasonably good success. Watch for: High-frequency level runs noticeably too hot regardless of placement - the reviewer tried four different setups (near/far from wall, on-axis, 30° off-axis) at two listening distances and couldn’t get it to sound right at any of…
Buy the KEF Q150. It ranks higher for sound quality than the Acoustic Energy AE100 Mk2 and costs less, so there is no real case for the other one.
Specifications Side By Side
| KEF Q150 | Acoustic Energy AE100 Mk2 | |
|---|---|---|
| Price | $350 Discontinued | $500 |
| Ranked | #14 of 34 in Medium Size Bookshelf Speakers | #23 of 34 in Medium Size Bookshelf Speakers |
| Bass Extension (-10dB) | 44Hz (measured, Erin’s Audio Corner) | 42Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) | 63Hz (measured, Erin’s Audio Corner) |
| Dimensions | 11.9"H x 7.1"W x 10.9"D (303 x 180 x 278 mm) | 11.4"H x 6.5"W x 9.8"D (290 x 165 x 250 mm) |
| Impedance | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin’s Audio Corner) | 6 ohms nominal, 4.7 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | ~85dB (300Hz-3kHz on-axis, measured, Erin’s Audio Corner) | 84dB (measured average, Erin’s Audio Corner) |
| Drivers | 130mm (5.25") aluminium Uni-Q woofer, 25mm (1") vented aluminium dome tweeter | 5.25" midwoofer, 1" soft fabric dome tweeter with waveguide |
| Discontinued | Yes | - |
| Weight | 12.3 lbs / 5.6 kg each | 20 lbs each |
| Woofer Cabinet | ported, rear | ported, rear slot port |
| Crossover Frequency | - | 2.9kHz |
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- KEF Q150 vs Klipsch RP-500M II
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The Two Speakers In Full
KEF Q150: $350 Discontinued Amazon
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.
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) |
| Dimensions | 11.9"H x 7.1"W x 10.9"D (303 x 180 x 278 mm) |
| Discontinued | Yes |
| 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) |
| Weight | 12.3 lbs / 5.6 kg each |
| Woofer Cabinet | ported, rear |
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- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: Kef’s Cheapest Bookshelf. Is the Q150 worth your money?
- Erin’s Audio Corner Website KEF Q150
- GR-Research: KEF Q150… can it get any BETTER?
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner: Budget Stereo Systems You Will Love
- Reddit Search for KEF Q150 Review
- Head-to-Head Comparisons
Acoustic Energy AE100 Mk2: $500 Amazon
Pros: Good directivity linearity - on-axis and off-axis response track each other well despite an otherwise uneven overall response, which means the tonal problems can be EQ’d out with reasonably good success. Wide horizontal radiation, about ±50°. Nicely finished cabinet - the reviewer specifically called out the fit and finish as a genuine positive. Both units of the review pair measured closely matched to each other.
Cons: High-frequency level runs noticeably too hot regardless of placement - the reviewer tried four different setups (near/far from wall, on-axis, 30° off-axis) at two listening distances and couldn’t get it to sound right at any of them. A mid-range dip that the reviewer attributes to internal cabinet resonance rather than intentional baffle-step compensation, reinforced by an internal inspection showing no cross-bracing and a slot port that may itself be resonating when tapped. Small tweeter waveguide magnet suggests limited power handling headroom. At this price and radiation pattern, the reviewer would pick the ELAC DBR62 (more neutral, similar ±60° pattern) or, for less money, the ELAC Debut 2.0 B6.2 over this speaker; the KEF Q150 and SVS Prime Bookshelf are also called out as more linear alternatives nearby in price.
Full Acoustic Energy AE100 Mk2 review and specifications →
| Bass Extension (-10dB) | 42Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 63Hz (measured, Erin's Audio Corner) |
| Crossover Frequency | 2.9kHz |
| Dimensions | 11.4"H x 6.5"W x 9.8"D (290 x 165 x 250 mm) |
| Drivers | 5.25" midwoofer, 1" soft fabric dome tweeter with waveguide |
| Impedance | 6 ohms nominal, 4.7 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 84dB (measured average, Erin's Audio Corner) |
| Weight | 20 lbs each |
| Woofer Cabinet | ported, rear slot port |
As an eBay Partner, we may be compensated if you make a purchase.
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons