Short answer: the AsciLab F6Bs on measured sound quality, the XTZ Spirit 4 on price. The AsciLab F6Bs ranks #20 of 130 bookshelf speakers at $799. The XTZ Spirit 4 ranks #92 at $477, $322 cheaper.
What the XTZ Spirit 4 offers: Substantial 6.5-inch stand-mount with a waveguided dome tweeter, adjustable treble level and port tuning. Spinorama predicts 44Hz in-room extension, broad roughly +/-60-degree horizontal coverage and a 5.39 preference score with a subwoofer. Watch for: The third-party measurement is low confidence. On-axis smoothness is only 0.248, directivity-index consistency is middling at 3.21, and the mildly downward -0.29dB/octave tonal slope contributes to a modest 3.27 raw preference score.
What the AsciLab F6Bs offers: A slimmer, sealed, VESA 100 wall mountable variant of AsciLab’s F6B, trading the F6B’s passive radiator for a shallower 15.4cm deep cabinet that can go straight on a wall bracket. The sound power directivity index has the tightest standard deviation, 3.32, of anything in this batch of new additions, meaning off axis energy tracks the on axis response unusually consistently for a sealed 2-way this size, and on axis deviation measures a clean 0.25dB average. Watch for: AsciLab’s own site shows the F6Bs sold out, though it remains in stock through resellers like Audiophonics and Tested Audio. Bass extension is measured at 82.0Hz at -3dB, noticeably less than the passive radiator equipped F6B, and listening window smoothness measures only a moderate 0.39. The 4 ohm nominal impedance calls for a reasonably capable amplifier.
Buy the XTZ Spirit 4 if the price matters more than sound quality. Buy the AsciLab F6Bs if sound quality matters more than the price.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| XTZ Spirit 4 | AsciLab F6Bs | |
|---|---|---|
| Price | $477 per pair | €799 per pair |
| Ranked | #92 of 130 in Large Size Bookshelf Speakers | #20 of 130 in Large Size Bookshelf Speakers |
| Enclosure | 2-way passive, rear-ported | sealed |
| Drivers | 1" dome tweeter, 6.5" woofer | 1" aluminum dome tweeter with waveguide and phase plug, 6" fiber cone woofer |
| Dimensions | 13.8H x 7.5W x 10.6D in | 14.5"H x 8"W x 6.1"D (368 x 203 x 154 mm) |
| Weight | 17.9 lbs (8.1 kg) each | 12.3 lbs (5.6 kg) each |
| Sensitivity | 86dB | 85.2dB @ 2.83V/1m (measured, Audio Science Review) |
| Impedance | 4 ohms | 4 ohms nominal, 3.7 ohms minimum |
| Spinorama Preference Score | 3.27 | 4.35 |
| Spinorama Preference Score with Perfect Sub | 5.39 | 7.01 |
| Bass Extension (-3dB) | - | 82.0Hz (measured, Audio Science Review) |
| Bass Extension (-10dB) | - | 50.1Hz (measured, Audio Science Review) |
| Crossover Frequency | - | 1kHz |
| Mounting | - | VESA 100 wall mount compatible |
| Warranty | - | 2 years |
| Country | - | South Korea |
| Maximum SPL | - | 100dB full bandwidth, 102dB above 100Hz (manufacturer specified) |
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Prices on this page were last checked September 16, 2026 at 12:41 AM 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
XTZ Spirit 4: $477 per pair XTZ eBay
Pros: Substantial 6.5-inch stand-mount with a waveguided dome tweeter, adjustable treble level and port tuning. Spinorama predicts 44Hz in-room extension, broad roughly +/-60-degree horizontal coverage and a 5.39 preference score with a subwoofer.
Cons: The third-party measurement is low confidence. On-axis smoothness is only 0.248, directivity-index consistency is middling at 3.21, and the mildly downward -0.29dB/octave tonal slope contributes to a modest 3.27 raw preference score.
Full XTZ Spirit 4 review and specifications →
| Dimensions | 13.8H x 7.5W x 10.6D in |
|---|---|
| Drivers | 1" dome tweeter, 6.5" woofer |
| Enclosure | 2-way passive, rear-ported |
| Impedance | 4 ohms |
| Sensitivity | 86dB |
| Spinorama Preference Score | 3.27 |
| Spinorama Preference Score with Perfect Sub | 5.39 |
| Weight | 17.9 lbs (8.1 kg) each |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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AsciLab F6Bs: €799 per pair Audiophonics eBay
Pros: A slimmer, sealed, VESA 100 wall mountable variant of AsciLab’s F6B, trading the F6B’s passive radiator for a shallower 15.4cm deep cabinet that can go straight on a wall bracket. The sound power directivity index has the tightest standard deviation, 3.32, of anything in this batch of new additions, meaning off axis energy tracks the on axis response unusually consistently for a sealed 2-way this size, and on axis deviation measures a clean 0.25dB average. Measured bass extension of 82.0Hz (-3dB), with a measured sensitivity of 85.2dB.
Cons: AsciLab’s own site shows the F6Bs sold out, though it remains in stock through resellers like Audiophonics and Tested Audio. Bass extension is measured at 82.0Hz at -3dB, noticeably less than the passive radiator equipped F6B, and listening window smoothness measures only a moderate 0.39. The 4 ohm nominal impedance calls for a reasonably capable amplifier.
Full AsciLab F6Bs review and specifications →
| Bass Extension (-10dB) | 50.1Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 82.0Hz (measured, Audio Science Review) |
| Country | South Korea |
| Crossover Frequency | 1kHz |
| Dimensions | 14.5"H x 8"W x 6.1"D (368 x 203 x 154 mm) |
| Drivers | 1" aluminum dome tweeter with waveguide and phase plug, 6" fiber cone woofer |
| Enclosure | sealed |
| Impedance | 4 ohms nominal, 3.7 ohms minimum |
| Maximum SPL | 100dB full bandwidth, 102dB above 100Hz (manufacturer specified) |
| Mounting | VESA 100 wall mount compatible |
| Sensitivity | 85.2dB @ 2.83V/1m (measured, Audio Science Review) |
| Spinorama Preference Score | 4.35 |
| Spinorama Preference Score with Perfect Sub | 7.01 |
| Warranty | 2 years |
| Weight | 12.3 lbs (5.6 kg) each |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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