Short answer: the Devialet Phantom Ultimate 98dB, if you are buying new. The Devialet Phantom II 98 dB ranks higher than the KEF LS50 Wireless II (#11 vs #19 of 108 powered bookshelf speakers) but is discontinued; its replacement, the Devialet Phantom Ultimate 98dB, is rated 4.4/5 at $3,998 and is still sold new.
The Phantom II 98 dB has far deeper bass from a tiny cabinet. Devialet’s own measurements show it reaching 30Hz before falling 3dB, with an even midrange spanning 2.3dB and a preference score of 6.87. Each 9.5 lbs (4.3 kg) unit has 400W and plays as a self-contained system. Stereo needs two units, and that deep bass may not hold at high volume.
The LS50 Wireless II is the more flexible stereo system. Its coaxial Uni-Q driver keeps the tone consistent above and below the tweeter, it reaches 51Hz before falling 3dB, and it has HDMI eARC, an analog input and streaming. KEF rates it to 108dB at 1m, louder than the Phantom’s 98dB. Its placement EQ presets are not true room correction.
Buy the Devialet Phantom Ultimate 98dB, the replacement for the discontinued Devialet Phantom II 98 dB; it is rated higher for sound quality than the KEF LS50 Wireless II.
Looking for alternatives? See the complete Powered Home rankings.
An all in one wireless stereo system with accurate, consistent sound, HDMI eARC and built in streaming.
A compact wireless streaming speaker with startlingly deep bass for its size and an even, well balanced sound.
Prices on this page were last checked October 31, 2026 at 7:11 PM 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.
Specifications Side By Side
| KEF LS50 Wireless II | Devialet Phantom II 98 dB | |
|---|---|---|
| Price | $2,999.99 per pair | $2,998 per pair Discontinued |
| Ranked | #19 of 108 in Medium Size Powered Bookshelf Speakers | #11 of 108 in Medium Size Powered Bookshelf Speakers |
| Bass Extension (-10dB) | 41.5Hz (measured, spinorama.org) | approximately 22.6Hz (measured, spinorama.org) |
| Bass Extension (-3dB) | 51.3Hz (measured, spinorama.org) | 30Hz (measured, spinorama.org) |
| Inputs | HDMI eARC, optical, digital coaxial, 3.5mm analog, USB-A (service), Ethernet | Wi-Fi, Ethernet, Bluetooth, AirPlay 2, Spotify Connect, UPnP, Roon Ready, analog/optical combo jack |
| Drivers | Uni-Q coincident array: 130mm aluminum woofer + 25mm MAT aluminum dome tweeter | One aluminum full-range driver; two aluminum bass drivers |
| App | KEF Connect (placement EQ presets, source selection, firmware updates) | - |
| Bluetooth | Yes | Yes |
| Bluetooth Version | 4.2 | 5.0 |
| EQ | Yes, fixed placement presets (desk/bookshelf/wall-mount) - no automatic room correction | - |
| Weight | 44.3 lbs (20.1 kg) for the pair | 9.5 lbs (4.3 kg) each |
| Amplifier Power | 280W (LF) + 100W (HF) per speaker, bi-amped | 400W RMS each |
| Dimensions | 12” x 7.9” x 12.2” (305 x 200 x 311 mm) each | 6.6 x 6.2 x 8.6 in each |
| Frequency Response | 45Hz - 28kHz ±3dB | 18Hz - 21kHz (-6dB) (Manufacturer specified) |
| Maximum SPL | 108dB at 1m (manufacturer specified) | 98dB at 1m each (manufacturer specified) |
| Spinorama Preference Score | 5.43 | 6.87 |
| Spinorama Preference Score with Perfect Sub | 7.51 | 7.95 |
| Subwoofer Output | Yes | - |
| Outputs | RCA subwoofer | - |
| XLR Input | No | No |
| RCA Input | No | No |
| TRS Input | No | No |
| Optical Input | Yes | Yes |
| Coaxial Input | Yes | No |
| USB Input | No | No |
| HDMI Input | Yes | No |
| AES Input | No | No |
| Aux Input | Yes | No |
| Bluetooth Codecs | - | SBC, AAC |
Related Speaker Comparisons
How Devialet Phantom II 98 dB compares with other leading options: