Short answer: the CBM-170 SE2 for a flatter default tuning, the RP-600M II if you want a speaker that responds well to correction. These rank #66 and #74 of 130 large bookshelf speakers, and the difference in price is only $18.01.
The CBM-170 SE2’s on-axis response is impressively flat from about 100Hz to 2kHz, staying within roughly ±1dB, with a clean, gradual bass rolloff below that and an estimated in-room response that tilts smoothly downward with no major discontinuities. Its one blemish is a narrow dip in the 3 to 5kHz range, down to about -2.7dB, mirrored by a matching dip in directivity that points to a brief widening of dispersion right at the tweeter/woofer crossover. This data comes from the manufacturer’s own Klippel measurements rather than an independent third party.
The RP-600M II runs hot in the treble on-axis, notably more so than the original RP-600M in some respects, and needs about 20 degrees of toe-out or the grille installed to sound balanced. Unusually, it is one of the rare speakers that measures better with its grille on. Where it excels is everything around that: a redesigned waveguide that extends flush to the baffle edge for less diffraction, roughly 10 to 20 degrees wider horizontal radiation than the original for more soundstage envelopment, and a major step up in tonal neutrality that largely eliminates the original RP-600M’s midrange resonance. Erin’s Audio Corner also found it responds well to EQ correction, letting the on-axis response be made genuinely linear with a miniDSP.
Bass extension is close: both measure -3dB around 70Hz, with the CBM-170 SE2 reaching -10dB at 50Hz against the RP-600M II’s 41Hz. The RP-600M II’s real sensitivity measures around 85 to 86dB despite Klipsch’s marketed 94.5dB spec, which is a half-space rating rather than an anechoic one; the CBM-170 SE2’s measured 86.8dB nearly matches its own 87dB spec.
Buy the CBM-170 SE2 if you want a speaker that sounds well-balanced straight out of the box with no toe-out or grille tricks needed.
Buy the RP-600M II if you’re willing to toe it in or leave the grille on, and you value its wider dispersion, refined binding posts for bi-amping, and proven response to EQ correction.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| Ascend CBM-170 SE2 | Klipsch RP-600M II | |
|---|---|---|
| Price | $468 per pair | $449.99 per pair |
| Ranked | #66 of 130 in Large Size Bookshelf Speakers | #74 of 130 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | 70Hz (measured, manufacturer spinorama data) | 70Hz (measured, Erin's Audio Corner) |
| Bass Extension (-10dB) | 50Hz (measured, manufacturer spinorama data) | 41Hz (measured, Erin's Audio Corner) |
| Sensitivity | 86.8dB (2.83V/1m, measured, manufacturer spinorama data; 87dB manufacturer specified) | 86dB (measured, Erin's Audio Corner) |
| Drivers | 27mm custom SEAS soft dome tweeter, 6.5" proprietary composite polygel cone woofer | 6.5" Cerametallic cone woofer, 1" titanium LTS vented tweeter with Tractrix horn |
| Dimensions | 12H x 9W x 9.5D in | 15.7"H x 8"W x 12.5"D (398.8 x 203.2 x 317.5 mm) |
| Weight | 15 lbs (6.8 kg) each | 13 lbs (5.9 kg) each |
| Impedance | 8 ohms | 8 ohms nominal (3.5 ohms minimum above 80Hz, measured by Erin's Audio Corner) |
| Power Handling | 200W continuous, 400W peak | - |
| Woofer Cabinet | ported, rear | ported |
| Spinorama Preference Score | 5.81 | 4.75 |
| Spinorama Preference Score with Perfect Sub | 8.17 | 6.88 |
Related Speaker Comparisons
How Ascend CBM-170 SE2 compares with other leading options:
- ELAC Debut 3.0 DB63 vs Ascend CBM-170 SE2
- Klipsch RP-600M II vs Revel M106
- Klipsch RP-600M II vs Selah Audio Purezza
- Klipsch RP-600M II vs Danley SH50
- Klipsch RP-600M II vs Wharfedale Diamond 9.1
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The Two Speakers In Full
Ascend CBM-170 SE2: $468 per pair Ascend Acoustics eBay
Pros: On-axis response is impressively flat from about 100Hz to 2kHz, staying within roughly ±1dB, with a clean, gradual bass rolloff below that. The directivity index rises smoothly and predictably through the crossover region, and the estimated in-room response shows a smooth, consistent downward tilt from 100Hz to 10kHz with no major discontinuities - close to the ideal in-room target shape. Measured sensitivity of 86.8dB nearly matches Ascend’s 87dB spec. The manufacturer’s own preference-score modeling comes out to 5.81 unequalized (rising to 8.17 with an ideal subwoofer, or 6.33/8.41 with EQ applied) - a strong result for a compact 2-way, and a clear step up from the original CBM-170 SE this replaces. Measured sensitivity of 86.8dB.
Cons: A narrow dip in the on-axis and listening-window response appears in the 3-5kHz range (down to about -2.7dB), mirrored by a matching dip in the directivity index at the same frequencies - likely a brief widening of dispersion right at the tweeter/woofer crossover. High-frequency directivity narrows substantially above 10kHz, typical for a small dome tweeter, so the top octave will sound more reserved off-axis than on-axis. Bass rolls off as expected for a compact 2-way monitor: -3dB around 70Hz and -10dB around 50Hz, so a subwoofer is needed for full-range use. This data comes from the manufacturer’s own Klippel measurements rather than an independent third-party review, so there’s no outside verification of channel matching, distortion, or unit-to-unit consistency.
Full Ascend CBM-170 SE2 review and specifications →
| Bass Extension (-10dB) | 50Hz (measured, manufacturer spinorama data) |
|---|---|
| Bass Extension (-3dB) | 70Hz (measured, manufacturer spinorama data) |
| Dimensions | 12H x 9W x 9.5D in |
| Drivers | 27mm custom SEAS soft dome tweeter, 6.5" proprietary composite polygel cone woofer |
| Impedance | 8 ohms |
| Power Handling | 200W continuous, 400W peak |
| Sensitivity | 86.8dB (2.83V/1m, measured, manufacturer spinorama data; 87dB manufacturer specified) |
| Spinorama Preference Score | 5.81 |
| Spinorama Preference Score with Perfect Sub | 8.17 |
| Weight | 15 lbs (6.8 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Klipsch RP-600M II: $449.99 per pair Amazon eBay
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) |
| 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 | 4.75 |
| Spinorama Preference Score with Perfect Sub | 6.88 |
| 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)
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