Short answer: the AsciLab C6B. It ranks #6 of 222 bookshelf speakers by sound quality, rated 4.7/5, at $1,145. The XTZ Spirit 4 ranks #159, rated 3.4/5, at $477, $668 cheaper, which does not close the gap in sound quality.
The AsciLab C6B is the more accurate, deeper-bass choice. Bookshelf speakers with very accurate sound and an unusually wide, stable soundstage, for any seating position. Its measured preference score, a predictor of how neutral it sounds, is 6.33 against 4.18 for the XTZ Spirit 4. Its bass reaches about 35Hz before falling 10dB, against 40Hz for the XTZ Spirit 4. The catch: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that.
What the XTZ Spirit 4 does well: Stand-mount speakers with a waveguide tweeter, adjustable treble and port tuning, wide coverage and fairly deep bass. The tradeoff: The third-party measurement is low confidence.
Buy the AsciLab C6B. It is rated higher for sound quality, and saving $668 with the XTZ Spirit 4 does not make up for the sound-quality gap.
Want more options? Browse the full Passive Home rankings.
Bookshelf speakers with very accurate sound and an unusually wide, stable soundstage, for any seating position.
Stand-mount speakers with a waveguide tweeter, adjustable treble and port tuning, wide coverage and fairly deep bass.
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Specifications Side By Side
| AsciLab C6B | XTZ Spirit 4 | |
|---|---|---|
| Price | $1145 per pair | $477 per pair |
| Ranked | #6 of 222 in Large Size Bookshelf Speakers | #159 of 222 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 35Hz (measured, Erin’s Audio Corner) | about 40.0Hz (measured, Spinorama data) |
| Bass Extension (-3dB) | 54Hz (measured, Erin’s Audio Corner) | 42Hz (manufacturer specified) |
| Dimensions | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) | 13.8H x 7.5W x 10.6D in |
| Impedance | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) | 4 ohms |
| Sensitivity | 85.6dB (measured, Erin’s Audio Corner) | 86dB |
| Drivers | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter | 1” dome tweeter, 6.5” woofer |
| Weight | 18.5 lbs (8.4 kg) each | 17.9 lbs (8.1 kg) each |
| Woofer Cabinet | passive radiator | - |
| Spinorama Preference Score | 6.33 | 4.18 |
| Spinorama Preference Score with Perfect Sub | 8.28 | 6.30 |
| DIY Kit | No | No |
| Enclosure | - | 2-way passive, rear-ported |
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