Short answer: the SunAudio Purified 4 4XA25A tw35mm. It ranks #24 of 168 bookshelf speakers by sound quality, rated 4.1/5, at $2,800; the Radiant Acoustics Clarity 4.2 ranks #39, rated 3.8/5, and costs $2,998, which makes this an easy call rather than a real tradeoff.
Why pick the SunAudio Purified 4 4XA25A tw35mm: A variant of the modular SunAudio Purified 4 with a Purifi 4” woofer and a BlieSMa 25mm aluminium dome tweeter in the configuration SunAudio labels tw35mm, each driver in its own CNC-machined aluminium sphere on a tripod stand. The catch: The 4” woofer limits bass to 73.4Hz (-3dB) and about 42Hz (-10dB), so it needs a subwoofer.
The Radiant Acoustics Clarity 4.2 is the deeper-bass option. Compact bookshelf design using a 4” Purifi mid-woofer with matching Purifi passive radiators and an AMT tweeter on a purpose-designed waveguide, built with genuine heft: aluminum baffle, extensive internal bracing and damping. Its bass reaches about 44Hz before falling 3dB, against 73.4Hz for the SunAudio Purified 4 4XA25A tw35mm. Watch for: Low sensitivity (rated 78dB, measured 78.5dB) is the trade-off for its bass extension: needs a fair amount of amplifier power, around 100W recommended for small-to-medium rooms versus the manufacturer’s own 60W baseline.
Buy the SunAudio Purified 4 4XA25A tw35mm. It is rated higher for sound quality than the Radiant Acoustics Clarity 4.2 and costs less, so only choose the other one for a particular feature it does better.
Still deciding? The full Passive Home rankings cover every ranked option.
Specifications Side By Side
| SunAudio Purified 4 4XA25A tw35mm | Radiant Acoustics Clarity 4.2 | |
|---|---|---|
| Price | $2,800 per pair | $2,998 per pair |
| Ranked | #24 of 168 in Medium Size Bookshelf Speakers | #39 of 168 in Medium Size Bookshelf Speakers |
| Drivers | A Purifi 4” woofer and a BlieSMa 25mm aluminium dome tweeter in the configuration SunAudio labels tw35mm | (2) 4” (102mm) woofer + AMT tweeter |
| Woofer Cabinet | sealed, separate spherical driver modules on tripod stand | passive radiator |
| Impedance | 4 ohms | 4 ohms |
| Bass Extension (-3dB) | 73.4Hz (measured, manufacturer spinorama data) | 44 Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | about 42Hz (measured, manufacturer spinorama data) | 35 Hz (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 6.14 (manufacturer spinorama data) | - |
| Spinorama Preference Score with Perfect Sub | 8.74 (manufacturer spinorama data) | - |
| Dimensions | 34.6” x 12.2” x 11” (880 x 310 x 280 mm) | 9.5”H x 6.3”W x 9.4”D (241 x 160 x 239 mm) |
| DIY Kit | No | No |
| Weight | - | 28.7 lbs (13 kg) (per pair: 57.3 lbs (26 kg)) |
| Sensitivity | - | 78 dB |
| Frequency Response | - | 40 Hz - 25 kHz |
| Recommended Power | - | 50-200W |
| Amplifier Power | - | External amplifier required |
Related Speaker Comparisons
How SunAudio Purified 4 4XA25A tw35mm compares with other leading options:
- SunAudio Purified 4 4XA25A Alu+Alu vs SunAudio Purified 4 4XA25A tw35mm
- SunAudio Purified 4 4XA25A Fiber+Alu vs SunAudio Purified 4 4XA25A tw35mm
- Audio First Fidelia vs Radiant Acoustics Clarity 4.2
- KEF LS50 Meta vs Radiant Acoustics Clarity 4.2
- Dynaudio X14 vs Radiant Acoustics Clarity 4.2
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 4XA25A tw35mm: $2,800 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 higher, rated 4.2/5), the SunAudio Purified 4 4XA25A Fiber+Alu (smaller bookshelf, ranked higher, rated 4.2/5) 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” woofer and a BlieSMa 25mm aluminium dome tweeter in the configuration SunAudio labels tw35mm, each driver in its own CNC-machined aluminium sphere on a tripod stand. SunAudio’s Klippel measurements show an exceptionally flat response (0.20 on-axis and 0.17 listening window deviation), for a preference score of 6.14 that reaches 8.74 with an ideal subwoofer.
Cons: The 4” woofer limits bass to 73.4Hz (-3dB) and about 42Hz (-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 tw35mm review and specifications →
| Bass Extension (-10dB) | about 42Hz (measured, manufacturer spinorama data) |
|---|---|
| Bass Extension (-3dB) | 73.4Hz (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” woofer and a BlieSMa 25mm aluminium dome tweeter in the configuration SunAudio labels tw35mm |
| Impedance | 4 ohms |
| Spinorama Preference Score | 6.14 (manufacturer spinorama data) |
| Spinorama Preference Score with Perfect Sub | 8.74 (manufacturer spinorama data) |
| Woofer Cabinet | sealed, separate spherical driver modules on tripod stand |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Radiant Acoustics Clarity 4.2: $2,998 per pair Radiant Acoustics eBay
Same family: the Radiant Acoustics Clarity 6.2 (larger bookshelf, rated 4.4/5) and the Radiant Acoustics Clarity 66 (floorstanding, rated 4.6/5).
Pros: Compact bookshelf design using a 4” Purifi mid-woofer with matching Purifi passive radiators and an AMT tweeter on a purpose-designed waveguide, built with genuine heft: aluminum baffle, extensive internal bracing and damping. Surprisingly wide horizontal dispersion (about ±70° through the midrange and into the treble), more enveloping than its larger 6.2 sibling despite the smaller cabinet. More linear on-axis than the bigger Radiant Acoustics Clarity 6.2, which needs 15-20° of toe-out to tame a rising treble; the 4.2 can be listened to closer to on-axis without that same correction. Wider-than-typical vertical dispersion (roughly +30°/-20°) for a two-way design, since its smaller woofer keeps the tweeter-to-woofer distance short. Genuinely deep bass extension for its size (F3 44Hz, reaching about 40Hz in-room), though it comes at a real cost to sensitivity. No resonance issues visible in impedance measurements. Measured bass extension of 44 Hz (-3dB).
Cons: Low sensitivity (rated 78dB, measured 78.5dB) is the trade-off for its bass extension: needs a fair amount of amplifier power, around 100W recommended for small-to-medium rooms versus the manufacturer’s own 60W baseline. Designed specifically for smaller rooms; the reviewer had to move testing out of his open-plan living room and into a smaller bedroom to avoid running into compression. A dip in the upper midrange gives a mild lack of attack and clarity, and a peak around 5kHz occasionally added a touch of extra sibilance. Multitone distortion crosses the reviewer’s 3% threshold at 96dB, making about 88dB a better average listening level; a slight upper-midrange bump persists even with an 80Hz high-pass filter applied. Dynamic range is limited: fine at 86dB, but the woofer starts giving up headroom by 96dB and drops off significantly by 102dB. Compared to its pricier sibling, the Radiant Acoustics Clarity 6.2, it has notably less dynamic range and higher multitone distortion, reflecting the smaller driver complement. A niche product size-wise: the reviewer couldn’t identify a clear direct competitor in the same size/price/SPL class.
Full Radiant Acoustics Clarity 4.2 review and specifications →
| Released | May 2025 (1 year ago) |
|---|---|
| Amplifier Power | External amplifier required |
| Bass Extension (-10dB) | 35 Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 44 Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 9.5”H x 6.3”W x 9.4”D (241 x 160 x 239 mm) |
| Drivers | (2) 4” (102mm) woofer + AMT tweeter |
| Frequency Response | 40 Hz - 25 kHz |
| Impedance | 4 ohms |
| Recommended Power | 50-200W |
| Sensitivity | 78 dB |
| Weight | 28.7 lbs (13 kg) (per pair: 57.3 lbs (26 kg)) |
| Woofer Cabinet | passive radiator |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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