Short answer: the AsciLab C6B. It ranks #6 of 203 bookshelf speakers by sound quality, rated 4.7/5, at $1,145. The Klipsch RP-600M II ranks #114, rated 3.7/5, at $449.99, $695.01 cheaper, a saving that is not big enough to make up the sound-quality gap.
Why pick the Klipsch RP-600M II: Redesigned waveguide extends flush to the baffle edge, reducing diffraction compared to the original RP-600M. The catch: On-axis, the treble runs notably hot (even hotter than the original RP-600M in some respects) and needs about 20° of toe-out or the grille installed to sound balanced.
The AsciLab C6B is the more accurate, deeper-bass choice. 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. Its measured preference score, a predictor of how neutral it sounds, is 6.33 against 5.64 for the Klipsch RP-600M II. Its bass reaches about 54Hz before falling 3dB, against 70Hz for the Klipsch RP-600M II. The catch: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that.
Buy the AsciLab C6B. It is rated higher for sound quality, and the $695.01 saving on the Klipsch RP-600M II is not enough to make up the difference.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Klipsch RP-600M II | AsciLab C6B | |
|---|---|---|
| Price | $449.99 per pair | $1145 per pair |
| Ranked | #114 of 203 in Large Size Bookshelf Speakers | #6 of 203 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 41Hz (measured, Erin’s Audio Corner) | 35Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 70Hz (measured, Erin’s Audio Corner) | 54Hz (measured, Erin’s Audio Corner) |
| Dimensions | 15.7”H x 8”W x 12.5”D (398.8 x 203.2 x 317.5 mm) | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) |
| Impedance | 8 ohms nominal (3.5 ohms minimum above 80Hz, measured by Erin’s Audio Corner) | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 86dB (measured, Erin’s Audio Corner) | 85.6dB (measured, Erin’s Audio Corner) |
| Drivers | 6.5” Cerametallic cone woofer, 1” titanium LTS vented tweeter with Tractrix horn | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter |
| Weight | 13 lbs (5.9 kg) each | 18.5 lbs (8.4 kg) each |
| Woofer Cabinet | ported | passive radiator |
| Spinorama Preference Score | 5.64 | 6.33 |
| Spinorama Preference Score with Perfect Sub | 7.77 | 8.28 |
| DIY Kit | No | No |
Related Speaker Comparisons
How AsciLab C6B compares with other leading options:
- AsciLab C6B vs Perlisten S4b
- AsciLab C6B vs KEF Reference 1 Meta
- AsciLab C6B vs GR-Research NX-Studio
- AsciLab C6B vs March Audio Sointuva AWG
- AsciLab C6B vs Audio First Cadentia 3
Prices on this page were last checked October 7, 2026 at 9:25 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
Klipsch RP-600M II: $449.99 per pair Amazon eBay
Older model: the Klipsch RP-600M (ranked lower, rated 2.9/5).
Same family: the Klipsch RP-500M II (smaller bookshelf, rated 4/5), the Klipsch RP-5000F II (smallest floorstanding, rated 4/5), the Klipsch RP-6000F II (floorstanding, rated 3.9/5), the Klipsch RP-8000F II (largest floorstanding, rated 3.9/5), the Klipsch RP-404C II (smallest center, rated 3.7/5), the Klipsch RP-500C II (center, rated 3.9/5) and the Klipsch RP-504C II (largest center, rated 3.8/5).
Pros: Redesigned waveguide extends flush to the baffle edge, reducing diffraction compared to the original RP-600M. Roughly 10-20° wider horizontal radiation than the original, giving more soundstage envelopment while retaining precise imaging. A major step up in overall tonal neutrality compared to the original RP-600M, largely eliminating that model’s midrange resonance issues. Unusually, sounds better with the grille on: the grille smooths out the elevated treble rather than degrading the sound, a rare trait among speakers the reviewer has tested. More refined back-panel hardware, including anodized binding posts and jumper cables for optional bi-amping. Responds well to EQ correction (verified using measurement software and a miniDSP), letting the on-axis response be made genuinely linear. Measured bass extension of 70Hz (-3dB), with a measured sensitivity of 86dB.
Cons: On-axis, the treble runs notably hot (even hotter than the original RP-600M in some respects) and needs about 20° of toe-out or the grille installed to sound balanced. Horizontal dispersion is very slightly less linear across angles than the original RP-600M, a minor trade-off for the wider overall radiation pattern. Klipsch’s marketed sensitivity (about 94.5dB) is, like the original, a half-space rating roughly 9dB above the anechoic reality (closer to 85-86dB). In-room bass rolls off around 60Hz in practice, and a 120Hz boost paired with a midrange scoop gives kick drums their “tambour” without real low-end weight: a subwoofer is still recommended. Vertical listening tolerance is limited to about ±10° from the tweeter axis. Toeing the speaker out for better on-axis tonality (rather than using the grille) introduces slightly more diffuse imaging from added sidewall reflections.
Full Klipsch RP-600M II review and specifications →
| Bass Extension (-10dB) | 41Hz (measured, Erin’s Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 70Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 15.7”H x 8”W x 12.5”D (398.8 x 203.2 x 317.5 mm) |
| Drivers | 6.5” Cerametallic cone woofer, 1” titanium LTS vented tweeter with Tractrix horn |
| Impedance | 8 ohms nominal (3.5 ohms minimum above 80Hz, measured by Erin’s Audio Corner) |
| Sensitivity | 86dB (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 5.64 |
| Spinorama Preference Score with Perfect Sub | 7.77 |
| Weight | 13 lbs (5.9 kg) each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: The Truth about Klipsch’s “NEW” Sound. RP-600M Update. More from Erin’s Audio Corner →
- Erin’s Audio Corner Website Klipsch RP-600M II
- GR-Research: We Bought The "NEW" RP-600M II Is KLIPSCH Listening?! More from GR-Research →
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner Measurements (spinorama.org)
- Erin’s Audio Corner: KEF Q1 Meta vs Emotiva vs Klipsch | The Real Differences
- Head-to-Head Comparisons
- Klipsch RP-600M II vs JBL 708i
- Klipsch RP-600M II vs PS Audio Aspen FR5
- Klipsch RP-600M II vs Theory Audio sb25
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- Klipsch RP-600M II vs Aoshida Audio Musician Knight I V2
- Klipsch RP-600M II vs Dynaudio Emit 20
- Klipsch RP-600M II vs MoFi SourcePoint 10 Master Edition
- Klipsch RP-600M II vs Philharmonic BMR Monitor
- See all 118 comparisons
AsciLab C6B: $1145 per pair Ascilab 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