Short answer: the PSI Audio A21-M. It ranks #27 of 119 powered bookshelf speakers by sound quality, rated 4.5/5, at $7,770; the Devialet Phantom Ultimate 108dB ranks #41, rated 4.4/5, and costs $7,998, so there is little reason to consider the other one.
The Devialet Phantom Ultimate 108dB is the more accurate, deeper-bass option. A single cabinet wireless speaker with astonishingly deep bass, nearly flat sound, and full streaming support for a complete music system. Its measured preference score, a predictor of how neutral it sounds, is 6.73 against 6.07 for the PSI Audio A21-M. Its bass reaches about 21Hz before falling 3dB, against 39.6Hz for the PSI Audio A21-M. Watch for: DSP limiting and compression take over near maximum volume, so the deep bass you hear at moderate levels shrinks when you push it; Erin’s 96dB distortion test ran into the limiter.
The case for the PSI Audio A21-M: Analog studio monitors with broadly even mids and useful bass, using analog phase correction instead of DSP. The catch: The measured tonal result is good rather than a clear advance over less costly competitors.
Buy the PSI Audio A21-M. It is rated higher for sound quality than the Devialet Phantom Ultimate 108dB and costs less, which makes it the one to get unless you need something the other one does better.
Looking for alternatives? See the complete Powered Home rankings.
Prices on this page were last checked November 7, 2026 at 7:34 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.
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Specifications Side By Side
| Devialet Phantom Ultimate 108dB | PSI Audio A21-M | |
|---|---|---|
| Price | $7,998 per pair | $7,770 per pair |
| Ranked | #41 of 119 in Large Size Powered Bookshelf Speakers | #27 of 119 in Large Size Powered Bookshelf Speakers |
| Bass Extension (-3dB) | <21Hz (measured, Erin’s Audio Corner) | 39.6Hz (measured, Audio Science Review) |
| Bass Extension (-10dB) | <21Hz (measured, Erin’s Audio Corner) | 33.2Hz (measured, Audio Science Review) |
| Dimensions | 10”H x 9.7”W x 13.5”D (255 x 246 x 342 mm) | 15.7”H x 9.8”W x 11.8”D (400 x 250 x 300 mm) |
| Weight | 24.5 lbs (11.1 kg) each | 28.2 lbs (12.8 kg) each |
| Drivers | Aluminum tweeter, aluminum midrange, two opposed aluminum woofers | 27mm handmade dome tweeter, 172mm cone woofer |
| Inputs | Wi-Fi, Ethernet, Bluetooth, Optical | XLR (balanced analog) |
| App | Yes (Devialet) | - |
| Bluetooth | Yes | No |
| Bluetooth Version | 5.3 | - |
| Bluetooth Codecs | SBC, AAC | - |
| Wi-Fi | Yes (Wi-Fi 6, dual-band) | - |
| Streaming Services | Yes (AirPlay 2, Google Cast, Spotify Connect, TIDAL Connect, Roon Ready, UPnP) | - |
| Amplifier Power | 1,100W total | 335W total (280W woofer, 55W tweeter, Class A/B) |
| Maximum SPL | 108dB (manufacturer specified) | 110dB short term, 121dB peak (manufacturer specified) |
| Frequency Response | 14Hz - 35kHz (Manufacturer specified) | 38Hz-23kHz -6dB |
| Spinorama Preference Score | 6.73 | 6.07 |
| Spinorama Preference Score with Perfect Sub | 7.38 | 7.72 |
| Subwoofer Output | No | - |
| XLR Input | No | Yes |
| RCA Input | No | No |
| TRS Input | No | No |
| Optical Input | Yes | No |
| Coaxial Input | No | No |
| USB Input | No | No |
| HDMI Input | No | No |
| AES Input | No | No |
| Aux Input | No | No |
| Enclosure | - | ported |
| Crossover Frequency | - | 2.4kHz |
| Warranty | - | 5+1 years |
| Country | - | Switzerland |
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