Short answer: the AsciLab C6B, unless you find a used GR-Research X-LS Encore. The X-LS Encore is described as an amazing value, but its on-axis response shows a slight depression in the upper bass and some peaking in the lower bass. At $1,145 versus $1,300, the C6B is the cheaper of the two, and its bass still rolls off around 50Hz in-room (F3 54Hz, F10 35Hz).
Buy the AsciLab C6B. It is rated higher for sound quality than the GR-Research X-LS Encore and costs less, so only choose the other one for a particular feature it does better.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| AsciLab C6B | GR-Research X-LS Encore | |
|---|---|---|
| Price | $1145 per pair | $1300 per pair |
| Ranked | #6 of 216 in Large Size Bookshelf Speakers | #141 of 216 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 35Hz (measured, Erin’s Audio Corner) | 44Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 54Hz (measured, Erin’s Audio Corner) | 64Hz (measured, Audio Science Review) |
| Dimensions | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) | 13.5”H x 8.5”W x 12.1”D (342.9 x 215.9 x 308 mm) |
| Impedance | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) | 8 ohms |
| Sensitivity | 85.6dB (measured, Erin’s Audio Corner) | 84.4dB (measured by Audio Science Review on the kit; 87dB manufacturer specified) |
| Drivers | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter | 6.5” Peerless M-165 paper composite cone, non-resonant polymer frame woofer, 1” Peerless India T26SG tweeter |
| Weight | 18.5 lbs (8.4 kg) each | 17 lbs (7.7 kg) each |
| Woofer Cabinet | passive radiator | ported |
| Spinorama Preference Score | 6.33 | 5.05 (measured, spinorama.org) |
| Spinorama Preference Score with Perfect Sub | 8.28 | 7.42 (measured, spinorama.org) |
| DIY Kit | 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. The two were measured by different sources, so small differences, especially in the bass, can come from the measurement setup rather than the speakers.
Measurement data: AsciLab C6B (measured by Erin’s Audio Corner) and GR-Research X-LS Encore (measured by Audio Science Review), via spinorama.org.
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Prices on this page were last checked October 14, 2026 at 2:38 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
AsciLab C6B: $1145 per pair Ascilab $1145 eBay
Same family: the AsciLab C5B (smaller bookshelf, rated 4.2/5).
Pros: Two-way design pairing a 1” aluminum ceramic dome tweeter on a large waveguide with a 6” aluminum ceramic cone woofer, crossed over at 1.1kHz, plus a rear passive radiator. Unusual trait: horizontal radiation actually widens at higher frequencies instead of narrowing like most two-way designs, which keeps image focus and soundstage depth consistent whether you toe the speakers in or out (5-10° off-axis was the sweet spot in testing). Vertical radiation also stays wide straight through the 2kHz crossover region, so the sound doesn’t collapse when standing up: unusual at this price. CA2034 measurements show strong on-axis linearity, listening window, early reflections, and directivity. Midrange and tweeter distortion stay very low even at 96dB, holding up against a $5,900 Arendal speaker in that regard despite roughly a 5x price gap. At $1145 shipped to the US, the reviewer calls it the best-value bookshelf speaker he’s tested, rivaling speakers 2-5x the price. Measured bass extension of 54Hz (-3dB), with a measured sensitivity of 85.6dB.
Cons: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that. Low-frequency harmonic distortion increases substantially at 96dB versus 86dB, though it’s second-order and less audible than it looks on paper. Minimum impedance dips to 2.6 ohms (EPDR as low as 1.2 ohms), so it wants an amplifier comfortable driving 4-ohm loads, ideally 100W or more. At 102dB, compression noticeably eats into midrange, bass, and some treble output. Shipping to the US adds roughly $200 on top of AsciLab’s list price. Against the reviewer’s reference Audiofirst Fidelia at a similar price, has slightly less lower-midrange body (about 1dB difference) and a smaller perceived soundstage size.
Full AsciLab C6B review and specifications →
| Bass Extension (-10dB) | 35Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 54Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) |
| Drivers | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter |
| Impedance | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 85.6dB (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 6.33 |
| Spinorama Preference Score with Perfect Sub | 8.28 |
| Weight | 18.5 lbs (8.4 kg) each |
| Woofer Cabinet | passive radiator |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
GR-Research X-LS Encore: $1300 per pair GR Research $1300 eBay
Pros: An amazing value for a speaker that measures this well. It is sold as a finished speaker, and anyone willing to build the cabinets and crossover can save a lot with the X-LS Encore kit. CEA2034 spinorama shows a generally flat on-axis response, especially in the listening window. Predicted in-room response is generally smooth and on-target. Distortion at 86dB SPL/1m is pretty clean above 200Hz. Measured bass extension of 64Hz (-3dB), with a measured sensitivity of 84.4dB.
Cons: A slight depression in the upper bass and some peaking in the lower bass shows up on-axis, along with directivity error in the crossover region. Vertical directivity requires staying within about 20 degrees of the tweeter axis. At 96dB SPL/1m distortion becomes “rather unhappy,” with bass distortion, a possible woofer issue around 2kHz, and a tweeter problem above 7kHz. The finished pair is built to order with a lead time of 3 to 5 weeks.
Full GR-Research X-LS Encore review and specifications →
| Released | Jul 2020 (6 years ago) |
|---|---|
| Bass Extension (-10dB) | 44Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 64Hz (measured, Audio Science Review) |
| Dimensions | 13.5”H x 8.5”W x 12.1”D (342.9 x 215.9 x 308 mm) |
| Drivers | 6.5” Peerless M-165 paper composite cone, non-resonant polymer frame woofer, 1” Peerless India T26SG tweeter |
| Impedance | 8 ohms |
| Sensitivity | 84.4dB (measured by Audio Science Review on the kit; 87dB manufacturer specified) |
| Spinorama Preference Score | 5.05 (measured, spinorama.org) |
| Spinorama Preference Score with Perfect Sub | 7.42 (measured, spinorama.org) |
| Weight | 17 lbs (7.7 kg) each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
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