Short answer: the Devialet Phantom II 98 dB for better sound quality, the KEF LSX II LT for the lower price. The Devialet Phantom II 98 dB ranks #10 of 64 powered bookshelf speakers at $2998. The KEF LSX II LT ranks #27 at $469.99, $2528.01 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 Devialet Phantom II 98 dB offers: Exceptional bass for its tiny sealed enclosure measures 30Hz at -3dB, 25.8Hz at -6dB, and 22.4Hz at -12dB, with a well-damped 0.302 low-frequency Q. The 2.58 sound-power directivity-index standard deviation indicates broad, consistent dispersion, and preference scores reach 6.07 without a subwoofer and 7.15 with one. Each speaker integrates amplification, Wi-Fi, AirPlay 2, Spotify Connect, Roon, Bluetooth, Ethernet, and optical/analog input. Watch for: The medium-quality manufacturer measurement has a 2.3dB reference band and 0.590dB on-axis average absolute deviation, good rather than class-leading linearity. Stereo requires two individually powered network speakers and costs nearly $3,000; maximum output is rated at 98dB at 1m per speaker, and the all-in-one architecture offers less serviceability and system flexibility than conventional monitors.
Buy the KEF LSX II LT if the price matters more than sound quality. Buy the Devialet Phantom II 98 dB if sound quality matters more than the price.
Specifications Side By Side
| KEF LSX II LT | Devialet Phantom II 98 dB | |
|---|---|---|
| Price | $469.99 | $2,998/pair |
| Ranked | #27 of 64 in Medium Size Powered Bookshelf Speakers | #10 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) | 6.6 x 6.2 x 8.6 in each |
| Inputs | Wifi, USB-C, HDMI, Optical, Bluetooth | Wi-Fi, Ethernet, Bluetooth, AirPlay 2, Spotify Connect, UPnP, Roon Ready, analog/optical combo jack |
| Outputs | RCA Subwoofer | - |
| Drivers | 115mm (4.5in.) magnesium/aluminium alloy cone woofer, 19mm (0.75in.) aluminium dome tweeter | One aluminum full-range driver; two aluminum bass drivers |
| Weight | 15 lbs / 6.8 kg | 9.5 lb each |
| App | No | - |
| Bluetooth | No | - |
| EQ | No | - |
| Output Power | 100w RMS Per Speaker | 400W RMS each |
| Bass Extension (-3dB) | 55Hz (measured, Erin’s Audio Corner) | 30Hz (measured, spinorama.org) |
| Bass Extension (-10dB) | 46Hz (measured, Erin’s Audio Corner) | approximately 22.6Hz (measured, spinorama.org) |
| Sensitivity | 84dB (measured at 0.3V/1m, Erin’s Audio Corner) | - |
| Max SPL | - | 98dB at 1m each |
Related Speaker Comparisons
More useful head-to-heads from the same speaker class:
- Kali Audio SM-5 vs JBL 305P MKII
- JBL 305P MKII vs KEF LS50 Wireless II
- Kali Audio SM-5 vs Dayton Audio M4
- KEF LSX II LT vs KEF LS50 Wireless II
- KEF LSX II LT vs Kali Audio SM-5
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.
As an eBay Partner, we may be compensated if you make a purchase.
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 |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- KEF LSX II LT vs Dayton Audio M4
- KEF LSX II LT vs Reflector Audio Square Two
- KEF LSX II LT vs Edifier S2000MKIII
- KEF LSX II LT vs Mackie MR524
- KEF LSX II LT vs KRK Classic 5
- KEF LSX II LT vs Sigberg Audio SBS Gen 2
- KEF LSX II LT vs Edifier MR4
- KEF LSX II LT vs HEDD Type 05 A-CORE
- See all 64 comparisons
Devialet Phantom II 98 dB: $2,998/pair Devialet eBay
Pros: Exceptional bass for its tiny sealed enclosure measures 30Hz at -3dB, 25.8Hz at -6dB, and 22.4Hz at -12dB, with a well-damped 0.302 low-frequency Q. The 2.58 sound-power directivity-index standard deviation indicates broad, consistent dispersion, and preference scores reach 6.07 without a subwoofer and 7.15 with one. Each speaker integrates amplification, Wi-Fi, AirPlay 2, Spotify Connect, Roon, Bluetooth, Ethernet, and optical/analog input.
Cons: The medium-quality manufacturer measurement has a 2.3dB reference band and 0.590dB on-axis average absolute deviation, good rather than class-leading linearity. Stereo requires two individually powered network speakers and costs nearly $3,000; maximum output is rated at 98dB at 1m per speaker, and the all-in-one architecture offers less serviceability and system flexibility than conventional monitors.
Full Devialet Phantom II 98 dB review and specifications →
| Bass Extension (-10dB) | approximately 22.6Hz (measured, spinorama.org) |
|---|---|
| Bass Extension (-3dB) | 30Hz (measured, spinorama.org) |
| Dimensions | 6.6 x 6.2 x 8.6 in each |
| Drivers | One aluminum full-range driver; two aluminum bass drivers |
| Inputs | Wi-Fi, Ethernet, Bluetooth, AirPlay 2, Spotify Connect, UPnP, Roon Ready, analog/optical combo jack |
| Max SPL | 98dB at 1m each |
| Output Power | 400W RMS each |
| Weight | 9.5 lb each |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Devialet Phantom II 98 dB vs JBL 305P MKII
- Devialet Phantom II 98 dB vs Kali LP-UNF
- Devialet Phantom II 98 dB vs Adam Audio T5V
- Devialet Phantom II 98 dB vs Yamaha HS5
- Devialet Phantom II 98 dB vs Neumann KH80 DSP
- Devialet Phantom II 98 dB vs Kali Audio IN-5
- Devialet Phantom II 98 dB vs IK Multimedia iLoud MTM MKII
- Devialet Phantom II 98 dB vs Edifier S2000MKIII
- See all 10 comparisons