Short answer: the SunAudio Purified 4 4XA25B Alu+Beryllium. It ranks #12 of 168 bookshelf speakers by sound quality, rated 4.3/5, at $3,650. The SunAudio Purified 4 4XA25A Alu+Alu ranks #20, rated 4.2/5, at $3,300, $350 cheaper, not enough of a saving to outweigh the sound-quality gap.
Why pick the SunAudio Purified 4 4XA25B Alu+Beryllium: A variant of the modular SunAudio Purified 4 with a Purifi 4” aluminium cone woofer and a BlieSMa 25mm beryllium dome tweeter, each driver in its own CNC-machined aluminium sphere on a tripod stand. The catch: The 4” woofer limits bass to 70.3Hz (-3dB) and about 55Hz (-10dB), so it needs a subwoofer.
The case for the SunAudio Purified 4 4XA25A Alu+Alu: A variant of the modular SunAudio Purified 4 with a Purifi 4” aluminium cone woofer and a BlieSMa 25mm aluminium dome tweeter, each driver in its own CNC-machined aluminium sphere on a tripod stand. Watch for: The 4” woofer limits bass to 71.3Hz (-3dB) and about 54.7Hz (-10dB), so it needs a subwoofer.
Buy the SunAudio Purified 4 4XA25B Alu+Beryllium. It is rated higher for sound quality, and saving $350 with the SunAudio Purified 4 4XA25A Alu+Alu does not make up for the sound-quality gap.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| SunAudio Purified 4 4XA25B Alu+Beryllium | SunAudio Purified 4 4XA25A Alu+Alu | |
|---|---|---|
| Price | $3,650 per pair | $3,300 per pair |
| Ranked | #12 of 168 in Medium Size Bookshelf Speakers | #20 of 168 in Medium Size Bookshelf Speakers |
| Sensitivity | 84dB (manufacturer specified) | 84dB (manufacturer specified) |
| Drivers | A Purifi 4” aluminium cone woofer and a BlieSMa 25mm beryllium dome tweeter | A Purifi 4” aluminium cone woofer and a BlieSMa 25mm aluminium dome tweeter |
| Woofer Cabinet | sealed, separate spherical driver modules on tripod stand | sealed, separate spherical driver modules on tripod stand |
| Impedance | 4 ohms | 4 ohms |
| Bass Extension (-3dB) | 70.3Hz (measured, manufacturer spinorama data) | 71.3Hz (measured, manufacturer spinorama data) |
| Bass Extension (-10dB) | about 55Hz (measured, manufacturer spinorama data) | about 54.7Hz (measured, manufacturer spinorama data) |
| Spinorama Preference Score | 6.67 (manufacturer spinorama data) | 6.48 (manufacturer spinorama data) |
| Spinorama Preference Score with Perfect Sub | 9.38 (manufacturer spinorama data) | 9.22 (manufacturer spinorama data) |
| Dimensions | 34.6” x 12.2” x 11” (880 x 310 x 280 mm) | 34.6” x 12.2” x 11” (880 x 310 x 280 mm) |
| DIY Kit | No | No |
Frequency Response Compared
Both speakers’ spinorama measurements, overlaid. A flatter line is more neutral: peaks sound forward or harsh, dips sound recessed. Each curve is shifted so its average from 300 Hz to 3 kHz sits at 0 dB, so loudness differences between the two are removed and only the shape is compared.
Measurement data: SunAudio Purified 4 4XA25B Alu+Beryllium (measured by the manufacturer) and SunAudio Purified 4 4XA25A Alu+Alu (measured by the manufacturer), via spinorama.org.
Related Speaker Comparisons
How SunAudio Purified 4 4XA25B Alu+Beryllium compares with other leading options:
- SunAudio Purified 4 vs SunAudio Purified 4 4XA25B Alu+Beryllium
- SunAudio Purified 4 4XA25B Alu+Beryllium vs SunAudio Purified 4 4XA25A Fiber+Alu
- SunAudio Purified 4 vs SunAudio Purified 4 4XA25A Alu+Alu
- SunAudio Purified 4 4XA25A Alu+Alu vs SunAudio Purified 4 4XA25A Fiber+Alu
- SunAudio Purified 4 4XA25A Alu+Alu vs SunAudio Purified 4 4XA25A tw35mm
Prices on this page were last checked October 11, 2026 at 4:59 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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The Two Speakers In Full
SunAudio Purified 4 4XA25B Alu+Beryllium: $3,650 per pair SunAudio eBay
Same family: the SunAudio Purified 4 (smaller bookshelf, ranked higher, rated 4.3/5), the SunAudio Purified 4 4XA25A Alu+Alu (smaller bookshelf, ranked lower, rated 4.2/5), the SunAudio Purified 4 4XA25A Fiber+Alu (smaller bookshelf, ranked lower, rated 4.2/5) and the SunAudio Purified 4 4XA25A tw35mm (smaller bookshelf, ranked lower, rated 4.1/5).
Pros: A variant of the modular SunAudio Purified 4 with a Purifi 4” aluminium cone woofer and a BlieSMa 25mm beryllium dome tweeter, each driver in its own CNC-machined aluminium sphere on a tripod stand. SunAudio’s Klippel measurements show an exceptionally flat response (0.13 on-axis and 0.08 listening window deviation), for a preference score of 6.67 that reaches 9.38 with an ideal subwoofer.
Cons: The 4” woofer limits bass to 70.3Hz (-3dB) and about 55Hz (-10dB), so it needs a subwoofer. The data comes from SunAudio and uses its reference DSP crossover, which the buyer has to reproduce, and no independent measurement exists. It needs separate amplification and DSP for each driver.
Full SunAudio Purified 4 4XA25B Alu+Beryllium review and specifications →
| Bass Extension (-10dB) | about 55Hz (measured, manufacturer spinorama data) |
|---|---|
| Bass Extension (-3dB) | 70.3Hz (measured, manufacturer spinorama data) |
| DIY Kit | No |
| Dimensions | 34.6” x 12.2” x 11” (880 x 310 x 280 mm) |
| Drivers | A Purifi 4” aluminium cone woofer and a BlieSMa 25mm beryllium dome tweeter |
| Impedance | 4 ohms |
| Sensitivity | 84dB (manufacturer specified) |
| Spinorama Preference Score | 6.67 (manufacturer spinorama data) |
| Spinorama Preference Score with Perfect Sub | 9.38 (manufacturer spinorama data) |
| Woofer Cabinet | sealed, separate spherical driver modules on tripod stand |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
SunAudio Purified 4 4XA25A Alu+Alu: $3,300 per pair SunAudio eBay
Same family: the SunAudio Purified 4 (smaller bookshelf, ranked higher, rated 4.3/5), the SunAudio Purified 4 4XA25A Fiber+Alu (larger bookshelf, ranked lower, rated 4.2/5), the SunAudio Purified 4 4XA25A tw35mm (larger bookshelf, ranked lower, rated 4.1/5) and the SunAudio Purified 4 4XA25B Alu+Beryllium (larger bookshelf, ranked higher, rated 4.3/5).
Pros: A variant of the modular SunAudio Purified 4 with a Purifi 4” aluminium cone woofer and a BlieSMa 25mm aluminium dome tweeter, each driver in its own CNC-machined aluminium sphere on a tripod stand. SunAudio’s Klippel measurements show an exceptionally flat response (0.19 on-axis and 0.11 listening window deviation), for a preference score of 6.48 that reaches 9.22 with an ideal subwoofer.
Cons: The 4” woofer limits bass to 71.3Hz (-3dB) and about 54.7Hz (-10dB), so it needs a subwoofer. The data comes from SunAudio and uses its reference DSP crossover, which the buyer has to reproduce, and no independent measurement exists. It needs separate amplification and DSP for each driver.
Full SunAudio Purified 4 4XA25A Alu+Alu review and specifications →
| Bass Extension (-10dB) | about 54.7Hz (measured, manufacturer spinorama data) |
|---|---|
| Bass Extension (-3dB) | 71.3Hz (measured, manufacturer spinorama data) |
| DIY Kit | No |
| Dimensions | 34.6” x 12.2” x 11” (880 x 310 x 280 mm) |
| Drivers | A Purifi 4” aluminium cone woofer and a BlieSMa 25mm aluminium dome tweeter |
| Impedance | 4 ohms |
| Sensitivity | 84dB (manufacturer specified) |
| Spinorama Preference Score | 6.48 (manufacturer spinorama data) |
| Spinorama Preference Score with Perfect Sub | 9.22 (manufacturer spinorama data) |
| Woofer Cabinet | sealed, separate spherical driver modules on tripod stand |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons