Short answer: the Ascend Acoustics CBM-170 SE2. It ranks #114 of 222 bookshelf speakers by sound quality, rated 3.8/5, at $468; the Polk Reserve R100 ranks #160, rated 3.4/5, and costs $559, so there is little reason to consider the other one.
The Ascend Acoustics CBM-170 SE2 is the more accurate option. On-axis response is impressively flat from about 100Hz to 2kHz, staying within roughly ±1dB, with a clean, gradual bass rolloff below that. Its measured preference score, a predictor of how neutral it sounds, is 6.30 against 5.46 for the Polk Reserve R100. The catch: 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.
The case for the Polk Reserve R100: Compact cabinet, unusually useful bass for its size and well-controlled woofer breakup. Watch for: Erin measured only about 85dB sensitivity and the impedance reaches 3.6 ohms, so it is neither efficient nor an entirely benign AVR load.
Buy the Ascend Acoustics CBM-170 SE2. It is rated higher for sound quality than the Polk Reserve R100 and costs less, which makes it the one to get unless you need something the other one does better.
Want more options? Browse the full Passive Home rankings.
Specifications Side By Side
| Ascend Acoustics CBM-170 SE2 | Polk Reserve R100 | |
|---|---|---|
| Price | $468 per pair | $559.00 per pair |
| Ranked | #114 of 222 in Large Size Bookshelf Speakers | #160 of 222 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | 70Hz (measured, manufacturer spinorama data) | 68Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 50Hz (measured, manufacturer spinorama data) | 49Hz (measured, Erin’s Audio Corner) |
| Sensitivity | 86.8dB (2.83V/1m, measured, manufacturer spinorama data; 87dB manufacturer specified) | 85dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Drivers | 27mm custom SEAS soft dome tweeter, 6.5” proprietary composite polygel cone woofer | 1” Pinnacle ring-radiator tweeter; 5.25” Turbine Cone midwoofer |
| Dimensions | 12H x 9W x 9.5D in | 12.8”H x 6.5”W x 10.2”D |
| Weight | 15 lbs (6.8 kg) each | 12.1 lbs (5.5 kg) each |
| Impedance | 8 ohms | 3.6 ohms minimum (measured, Erin’s Audio Corner) |
| Power Handling | 200W continuous, 400W peak | - |
| Woofer Cabinet | ported, rear | ported, rear X-Port |
| Spinorama Preference Score | 6.30 | 5.46 |
| Spinorama Preference Score with Perfect Sub | 8.66 | 7.93 |
| DIY Kit | No | 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: Ascend Acoustics CBM-170 SE2 (measured by the manufacturer) and Polk Reserve R100 (measured by Erin’s Audio Corner), via spinorama.org.
Related Speaker Comparisons
How Ascend Acoustics CBM-170 SE2 compares with other leading options:
- Ascend Acoustics CBM-170 SE2 vs Perlisten S4b
- Ascend Acoustics CBM-170 SE2 vs KEF Reference 1 Meta
- Ascend Acoustics CBM-170 SE2 vs GR-Research NX-Studio
- AsciLab C6B vs Ascend Acoustics CBM-170 SE2
- Ascend Acoustics CBM-170 SE2 vs Audio First Cadentia 3
Prices on this page were last checked October 15, 2026 at 5:41 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
Ascend Acoustics CBM-170 SE2: $468 per pair Ascend Acoustics $468 eBay
Older model: the Ascend Acoustics CBM-170 SE (ranked lower, rated 2.1/5). See every Ascend CBM, HTM and CMT generation.
Same family: the Ascend Acoustics HTM-200SE2 (larger bookshelf, rated 4.3/5) and the Ascend Acoustics CMT-340 SE2 (larger bookshelf, ranked higher, rated 4.4/5).
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 6.30 unequalized (rising to 8.66 with an ideal subwoofer, or 6.79/8.86 with EQ applied): a strong result for a compact 2-way, and a clear step up from the original Ascend Acoustics 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 Acoustics CBM-170 SE2 review and specifications →
| Released | Jul 2026 (3 months ago) |
|---|---|
| Bass Extension (-10dB) | 50Hz (measured, manufacturer spinorama data) |
| Bass Extension (-3dB) | 70Hz (measured, manufacturer spinorama data) |
| DIY Kit | No |
| 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 | 6.30 |
| Spinorama Preference Score with Perfect Sub | 8.66 |
| Weight | 15 lbs (6.8 kg) each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Ascend Acoustics CBM-170 SE2 vs Polk Signature Elite ES20
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- Ascend Acoustics CBM-170 SE2 vs Philharmonic BMR Monitor
- Ascend Acoustics CBM-170 SE2 vs Mission LX-3 MKII
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- Ascend Acoustics CBM-170 SE2 vs ELAC DBR62
- See all 48 comparisons
Polk Reserve R100: $559.00 per pair Amazon $559.00 Polk Audio $649 eBay
Same family: the Polk R200 (larger bookshelf, ranked lower, rated 3.2/5), the Polk Reserve R500 (smallest floorstanding, rated 4.2/5), the Polk Reserve R600 (floorstanding, estimated 4.2/5), the Polk Audio Reserve R700 (largest floorstanding, rated 4.3/5), the Polk Audio Reserve R300 (smallest center, estimated 3.6/5), the Polk Audio Reserve R350 (center, rated 3.7/5) and the Polk Audio Reserve R400 (largest center, estimated 3.8/5).
Pros: Compact cabinet, unusually useful bass for its size and well-controlled woofer breakup. Erin measured F3/F10 points of 68Hz/49Hz, and the X-Port vent avoids much of the chuffing and pipe resonance common to budget rear ports. The 5.25-inch Turbine Cone woofer and 1-inch Pinnacle ring-radiator tweeter produce good detail at moderate levels, while listening roughly 20° off-axis reduces part of the elevated top octave. Measured bass extension of 68Hz (-3dB), with a measured sensitivity of 85dB.
Cons: Erin measured only about 85dB sensitivity and the impedance reaches 3.6 ohms, so it is neither efficient nor an entirely benign AVR load. The treble runs roughly 3dB above the midrange and becomes aggressive above about 85dB SPL. A directivity discontinuity through the woofer/tweeter crossover means EQ cannot fully repair the power response, and a 400Hz impedance feature plus 500Hz-1kHz response irregularity suggests a cabinet or system resonance. Substantial low-frequency compression at higher playback levels limits clean dynamics.
Full Polk Reserve R100 review and specifications →
| Released | 2021 (5 years ago) |
|---|---|
| Bass Extension (-10dB) | 49Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 68Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 12.8”H x 6.5”W x 10.2”D |
| Drivers | 1” Pinnacle ring-radiator tweeter; 5.25” Turbine Cone midwoofer |
| Impedance | 3.6 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 85dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 5.46 |
| Spinorama Preference Score with Perfect Sub | 7.93 |
| Weight | 12.1 lbs (5.5 kg) each |
| Woofer Cabinet | ported, rear X-Port |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- Polk Reserve R100 vs Sonus Faber Lumina II
- Polk Reserve R100 vs Polk Monitor XT20
- Polk Reserve R100 vs KEF Q3 Meta
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- Polk Reserve R100 vs HSU Research MFL-6
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