Short answer: the KEF LSX II LT for better sound quality, the M-Audio BX4 D3 for the lower price. The KEF LSX II LT ranks #27 of 64 powered bookshelf speakers at $469.99. The M-Audio BX4 D3 ranks #56 at $149, $320.99 cheaper.
What the KEF LSX II LT offers: Coaxial (Uni-Q-style) driver keeps the tweeter centered in the midrange, giving wide and consistent dispersion both horizontally and vertically (about ±60° each) - a wide sweet spot for multiple seats or positions. The KEF Connect app provides genuinely useful DSP control: desk/wall boundary compensation, adjustable bass contour (standard/less/extra), treble trim, and subwoofer integration, letting you tune the sound to wherever it’s placed. Distortion at a moderate 86dB looks good for the speaker’s compact size. Tonal profile stays consistent from 0° to 30° off-axis, so side-seat listeners hear essentially the same balance as someone centered. Extensive connectivity for its size: HDMI, USB, optical, sub output, plus Wi-Fi/Bluetooth. Clearly outperformed the reviewer’s soundbars, including ones bundled with their own subwoofers, as a TV audio replacement. Watch for: Small drivers mean it’s SPL-limited: bass compression kicks in around 88-92dB/1m per speaker, and multitone distortion crosses the reviewer’s 3% threshold around 96dB - not intended for loud or large-room duty. F3 of 55Hz and F10 of 46Hz mean it loses much of its bass by around 50Hz; a subwoofer (controllable through the same app) is needed for real low end. Diffraction dips appear around 4-5kHz and again near 8kHz, likely tied to the tweeter housing or surround, giving a mild reduction in treble attack and sibilance. A possible port or enclosure resonance shows up around 800Hz in the rear-radiation measurements, though the reviewer wasn’t certain of the exact cause or whether it’s audible. No analog input on this LT variant, so a turntable can’t be connected directly - only the pricier standard LSX II model includes one.
What the M-Audio BX4 D3 offers: Affordable compact powered pair with 4.5-inch Kevlar woofers, rear EQ controls, balanced TRS, RCA and front-panel aux/headphone connections. Spinorama predicts a 5.14 preference score with a subwoofer and useful nearfield bass extension near 62Hz. Watch for: The third-party measurement is low confidence, and the small shared-amplifier design has limited output and bass headroom. Its raw no-subwoofer preference score is modest, the rear port complicates wall placement, and only the left cabinet contains amplification and controls.
Buy the KEF LSX II LT if sound quality matters more than the price. Buy the M-Audio BX4 D3 if the price matters more than sound quality.
If sound quality matters at all to you, skip the M-Audio BX4 D3. It ranks near the bottom of the 64 powered bookshelf speakers, so look higher up the list instead.
Specifications Side By Side
| KEF LSX II LT | M-Audio BX4 D3 | |
|---|---|---|
| Price | $469.99 | $149/pair |
| Ranked | #27 of 64 in Medium Size Powered Bookshelf Speakers | #56 of 64 in Medium Size Powered Bookshelf Speakers |
| Dimensions | 9.5"H x 6.1"W x 7.1"D (241.3 x 154.9 x 180.3 mm) | 8.9H x 6.1W x 6.9D in |
| Inputs | Wifi, USB-C, HDMI, Optical, Bluetooth | TRS, RCA, 3.5mm aux; headphone output |
| Outputs | RCA Subwoofer | - |
| Drivers | 115mm (4.5in.) magnesium/aluminium alloy cone woofer, 19mm (0.75in.) aluminium dome tweeter | 1" dome tweeter, 4.5" Kevlar woofer |
| Weight | 15 lbs / 6.8 kg | 9.8 lbs/pair |
| App | No | - |
| Bluetooth | No | - |
| EQ | No | - |
| Output Power | 100w RMS Per Speaker | - |
| Bass Extension (-3dB) | 55Hz (measured, Erin’s Audio Corner) | - |
| Bass Extension (-10dB) | 46Hz (measured, Erin’s Audio Corner) | - |
| Sensitivity | 84dB (measured at 0.3V/1m, Erin’s Audio Corner) | - |
| Enclosure | - | 2-way powered stereo pair, rear-ported |
| Power Output | - | 120W peak system |
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Prices on this page were last checked August 25, 2026 at 6:19 AM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
KEF LSX II LT: $469.99 Amazon eBay
Pros: Coaxial (Uni-Q-style) driver keeps the tweeter centered in the midrange, giving wide and consistent dispersion both horizontally and vertically (about ±60° each) - a wide sweet spot for multiple seats or positions. The KEF Connect app provides genuinely useful DSP control: desk/wall boundary compensation, adjustable bass contour (standard/less/extra), treble trim, and subwoofer integration, letting you tune the sound to wherever it’s placed. Distortion at a moderate 86dB looks good for the speaker’s compact size. Tonal profile stays consistent from 0° to 30° off-axis, so side-seat listeners hear essentially the same balance as someone centered. Extensive connectivity for its size: HDMI, USB, optical, sub output, plus Wi-Fi/Bluetooth. Clearly outperformed the reviewer’s soundbars, including ones bundled with their own subwoofers, as a TV audio replacement.
Cons: Small drivers mean it’s SPL-limited: bass compression kicks in around 88-92dB/1m per speaker, and multitone distortion crosses the reviewer’s 3% threshold around 96dB - not intended for loud or large-room duty. F3 of 55Hz and F10 of 46Hz mean it loses much of its bass by around 50Hz; a subwoofer (controllable through the same app) is needed for real low end. Diffraction dips appear around 4-5kHz and again near 8kHz, likely tied to the tweeter housing or surround, giving a mild reduction in treble attack and sibilance. A possible port or enclosure resonance shows up around 800Hz in the rear-radiation measurements, though the reviewer wasn’t certain of the exact cause or whether it’s audible. No analog input on this LT variant, so a turntable can’t be connected directly - only the pricier standard LSX II model includes one.
Full KEF LSX II LT review and specifications →
| App | No |
|---|---|
| Bass Extension (-10dB) | 46Hz (measured, Erin's Audio Corner) |
| Bass Extension (-3dB) | 55Hz (measured, Erin's Audio Corner) |
| Bluetooth | No |
| Dimensions | 9.5"H x 6.1"W x 7.1"D (241.3 x 154.9 x 180.3 mm) |
| Drivers | 115mm (4.5in.) magnesium/aluminium alloy cone woofer, 19mm (0.75in.) aluminium dome tweeter |
| EQ | No |
| Inputs | Wifi, USB-C, HDMI, Optical, Bluetooth |
| Output Power | 100w RMS Per Speaker |
| Outputs | RCA Subwoofer |
| Sensitivity | 84dB (measured at 0.3V/1m, Erin's Audio Corner) |
| Weight | 15 lbs / 6.8 kg |
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- Reviews, Comparisons and Sound Samples
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M-Audio BX4 D3: $149/pair Amazon eBay
Pros: Affordable compact powered pair with 4.5-inch Kevlar woofers, rear EQ controls, balanced TRS, RCA and front-panel aux/headphone connections. Spinorama predicts a 5.14 preference score with a subwoofer and useful nearfield bass extension near 62Hz.
Cons: The third-party measurement is low confidence, and the small shared-amplifier design has limited output and bass headroom. Its raw no-subwoofer preference score is modest, the rear port complicates wall placement, and only the left cabinet contains amplification and controls.
Full M-Audio BX4 D3 review and specifications →
| Dimensions | 8.9H x 6.1W x 6.9D in |
|---|---|
| Drivers | 1" dome tweeter, 4.5" Kevlar woofer |
| Enclosure | 2-way powered stereo pair, rear-ported |
| Inputs | TRS, RCA, 3.5mm aux; headphone output |
| Power Output | 120W peak system |
| Weight | 9.8 lbs/pair |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- M-Audio BX4 D3 vs Edifier R1280DB
- M-Audio BX4 D3 vs KRK Classic 5
- M-Audio BX4 D3 vs Edifier S2000MKIII
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