Short answer: the Radiant Acoustics Clarity 66 if sound quality matters most, the Klipsch Heresy IV if price matters most. The Radiant Acoustics Clarity 66 ranks #5 of 71 floorstanding speakers at $7998. The Klipsch Heresy IV ranks #44 at $3198, $4800 cheaper.
What the Radiant Acoustics Clarity 66 offers: ASR’s revised Spinorama measurement shows bass reaching 32.2Hz at -3dB and 27.8Hz at -6dB, giving substantial low-end weight without a subwoofer. The response spans 2.3dB from 300Hz to 5kHz, with preference scores of 5.10 standalone and 6.12 with an ideal subwoofer. The review’s exceptionally low bass distortion at ordinary levels complements that extension, while dual 6.5-inch Purifi woofers provide a strong foundation for full-range listening. Watch for: Vertical directivity is narrow and horizontal coverage is uneven, so listening height and placement affect tonal balance. Treble resonances and response irregularities keep it from reference-level neutrality. Spinorama’s modeled EQ improves the scores to 6.09 standalone and 6.99 with an ideal subwoofer, but those are corrected results, not stock performance. Measured sensitivity is 85.9dB at 2.83V/1m with a nominal 4-ohm load; use an amplifier comfortable driving 4 ohms. Distortion rises at very high playback levels.
What the Klipsch Heresy IV offers: Very high 94.5dB/2.83V/1m sensitivity in Erin’s anechoic measurement (well below Klipsch’s 99dB in-room claim, but still excellent) and strong short-term output from a 12-inch woofer plus horn-loaded midrange and tweeter. The compact, furniture-grade Heritage cabinet is easier to place than most high-efficiency designs, and dynamics at moderate levels can sound lively. A stable four-ohm-capable amplifier can produce substantial SPL with relatively little voltage. Watch for: Erin measured a 77Hz F3 and response rolling away near 100Hz in-room, so a subwoofer is required for modern full-range reproduction. The impedance dips to about 4 ohms, reducing the practical amplifier advantage implied by its sensitivity. Pronounced directivity mismatch at the driver transitions, impedance/response resonances and elevated distortion spikes around the crossover remain audible concerns that EQ cannot fully solve. At 102dB Erin measured roughly 1.5dB midband compression; at 96dB distortion rises around crossover. Performance is difficult to justify at the price, and Erin explicitly did not recommend it.
Buy the Radiant Acoustics Clarity 66 when sound quality outweighs the price for you, and the Klipsch Heresy IV when the price outweighs sound quality instead.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Radiant Acoustics Clarity 66 | Klipsch Heresy IV | |
|---|---|---|
| Price | $7,998 per pair | $3,198 per pair |
| Ranked | #5 of 71 in Large Size Floorstanding Speakers | #44 of 71 in Large Size Floorstanding Speakers |
| Bass Extension (-3dB) | 32.2Hz (measured, Audio Science Review) | 77Hz (measured, Erin's Audio Corner) |
| Bass Extension (-10dB) | 24.4Hz (measured, Audio Science Review) | 50.0Hz (measured, Erin's Audio Corner) |
| Sensitivity | 85.9dB (2.83V/1m, measured, Audio Science Review; 86dB manufacturer specified) | 94.5dB/2.83V/1m (measured, Erin's Audio Corner) |
| Drivers | Custom waveguide-loaded tweeter with beam-expansion fins, 2x 6.5" Purifi USHINDI aluminum-cone woofers | 1" horn-loaded tweeter; 1.75" horn-loaded midrange; 12" woofer |
| Dimensions | 40.4"H x 8.7"W x 14"D (1025 x 222 x 355 mm) | 24.8"H x 15.6"W x 13.3"D |
| Weight | 101.4 lbs (46 kg) each | 45 lbs (20.4 kg) each |
| Impedance | 4 ohms nominal | Approximately 4 ohms minimum (measured, Erin's Audio Corner) |
| Crossover Frequency | 2.4kHz | - |
| Woofer Cabinet | ported, large rear port | ported, rear |
| Spinorama Preference Score | 5.10 | 1.48 |
| Spinorama Preference Score with Perfect Sub | 6.12 | 4.23 |
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The Two Speakers In Full
Radiant Acoustics Clarity 66: $7,998 per pair Radiant Acoustics eBay
Pros: ASR’s revised Spinorama measurement shows bass reaching 32.2Hz at -3dB and 27.8Hz at -6dB, giving substantial low-end weight without a subwoofer. The response spans 2.3dB from 300Hz to 5kHz, with preference scores of 5.10 standalone and 6.12 with an ideal subwoofer. The review’s exceptionally low bass distortion at ordinary levels complements that extension, while dual 6.5-inch Purifi woofers provide a strong foundation for full-range listening. Measured bass extension of 32.2Hz (-3dB), with a measured sensitivity of 85.9dB.
Cons: Vertical directivity is narrow and horizontal coverage is uneven, so listening height and placement affect tonal balance. Treble resonances and response irregularities keep it from reference-level neutrality. Spinorama’s modeled EQ improves the scores to 6.09 standalone and 6.99 with an ideal subwoofer, but those are corrected results, not stock performance. Measured sensitivity is 85.9dB at 2.83V/1m with a nominal 4-ohm load; use an amplifier comfortable driving 4 ohms. Distortion rises at very high playback levels.
Full Radiant Acoustics Clarity 66 review and specifications →
| Bass Extension (-10dB) | 24.4Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 32.2Hz (measured, Audio Science Review) |
| Crossover Frequency | 2.4kHz |
| Dimensions | 40.4"H x 8.7"W x 14"D (1025 x 222 x 355 mm) |
| Drivers | Custom waveguide-loaded tweeter with beam-expansion fins, 2x 6.5" Purifi USHINDI aluminum-cone woofers |
| Impedance | 4 ohms nominal |
| Sensitivity | 85.9dB (2.83V/1m, measured, Audio Science Review; 86dB manufacturer specified) |
| Spinorama Preference Score | 5.10 |
| Spinorama Preference Score with Perfect Sub | 6.12 |
| Weight | 101.4 lbs (46 kg) each |
| Woofer Cabinet | ported, large rear port |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Radiant Acoustics Clarity 66 vs Ascend Acoustics ELX Ribbon Tower
- Radiant Acoustics Clarity 66 vs MoFi SourcePoint 888
- Radiant Acoustics Clarity 66 vs MoFi SourcePoint V10 Master Edition
- Radiant Acoustics Clarity 66 vs KEF Blade Two Meta
- Radiant Acoustics Clarity 66 vs Revel F328Be
- Radiant Acoustics Clarity 66 vs Revel F226Be
- Radiant Acoustics Clarity 66 vs JBL 4367
- Radiant Acoustics Clarity 66 vs Revel F228Be
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Klipsch Heresy IV: $3,198 per pair Amazon Crutchfield eBay
Pros: Very high 94.5dB/2.83V/1m sensitivity in Erin’s anechoic measurement (well below Klipsch’s 99dB in-room claim, but still excellent) and strong short-term output from a 12-inch woofer plus horn-loaded midrange and tweeter. The compact, furniture-grade Heritage cabinet is easier to place than most high-efficiency designs, and dynamics at moderate levels can sound lively. A stable four-ohm-capable amplifier can produce substantial SPL with relatively little voltage. Measured bass extension of 77Hz (-3dB), with a measured sensitivity of 94.5dB.
Cons: Erin measured a 77Hz F3 and response rolling away near 100Hz in-room, so a subwoofer is required for modern full-range reproduction. The impedance dips to about 4 ohms, reducing the practical amplifier advantage implied by its sensitivity. Pronounced directivity mismatch at the driver transitions, impedance/response resonances and elevated distortion spikes around the crossover remain audible concerns that EQ cannot fully solve. At 102dB Erin measured roughly 1.5dB midband compression; at 96dB distortion rises around crossover. Performance is difficult to justify at the price, and Erin explicitly did not recommend it.
Full Klipsch Heresy IV review and specifications →
| Bass Extension (-10dB) | 50.0Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 77Hz (measured, Erin's Audio Corner) |
| Dimensions | 24.8"H x 15.6"W x 13.3"D |
| Drivers | 1" horn-loaded tweeter; 1.75" horn-loaded midrange; 12" woofer |
| Impedance | Approximately 4 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 94.5dB/2.83V/1m (measured, Erin's Audio Corner) |
| Spinorama Preference Score | 1.48 |
| Spinorama Preference Score with Perfect Sub | 4.23 |
| Weight | 45 lbs (20.4 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
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