Short answer: the Ascend CBM-170 SE2. It ranks #66 of 131 bookshelf speakers by sound quality, rated 3.8/5, at $468. The Polk Monitor XT20 ranks #90, rated 3.4/5, at $279, $189 cheaper, not enough of a saving to outweigh the sound-quality gap.
The case for the Ascend CBM-170 SE2: On-axis response is impressively flat from about 100Hz to 2kHz, staying within roughly ±1dB, with a clean, gradual bass rolloff below that. 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 Monitor XT20: Two-way bookshelf design with a 1” tweeter and 6.5” woofer, part of Polk’s budget-friendly XT lineup (spanning roughly $200-700 across the series). The tradeoff: Notably bright treble, elevated roughly 1-5dB above the midrange depending on frequency - a characteristic shared across the whole Polk XT lineup, requiring either EQ or toe-out to tame.
Buy the Ascend CBM-170 SE2. It is rated higher for sound quality, and the $189 saving on the Polk Monitor XT20 is not enough to make up the difference.
Still deciding? The full Passive Home rankings cover every ranked option.
Specifications Side By Side
| Ascend CBM-170 SE2 | Polk Monitor XT20 | |
|---|---|---|
| Price | $468 per pair | $279.00 per pair |
| Ranked | #66 of 131 in Large Size Bookshelf Speakers | #90 of 131 in Large Size Bookshelf Speakers |
| Bass Extension (-3dB) | 70Hz (measured, manufacturer spinorama data) | 64.5Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 50Hz (measured, manufacturer spinorama data) | 43.4Hz (derived, log-interpolated between spinorama.org -9dB/-12dB points) |
| Sensitivity | 86.8dB (2.83V/1m, measured, manufacturer spinorama data; 87dB manufacturer specified) | 86dB (measured by Erin’s Audio Corner; 87dB manufacturer specified) |
| Drivers | 27mm custom SEAS soft dome tweeter, 6.5” proprietary composite polygel cone woofer | 6.5” bilaminate paper cone woofer, 1” Terylene dome tweeter |
| Dimensions | 12H x 9W x 9.5D in | 13”H x 7.5”W x 11”D (330.2 x 190.5 x 279.4 mm) |
| Weight | 15 lbs (6.8 kg) each | 11.9 lbs (5.4 kg) each |
| Impedance | 8 ohms | 8 ohms nominal (measured, Erin’s Audio Corner) |
| Power Handling | 200W continuous, 400W peak | - |
| Woofer Cabinet | ported, rear | ported |
| Spinorama Preference Score | 6.30 | 4.71 |
| Spinorama Preference Score with Perfect Sub | 8.66 | 7.07 |
| DIY Kit | No | No |
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Prices on this page were last checked September 26, 2026 at 11:14 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 CBM-170 SE2: $468 per pair Ascend Acoustics eBay
Older model: the Ascend CBM-170 SE (rated 2.1/5).
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 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) |
| 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
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Polk Monitor XT20: $279.00 per pair Amazon Crutchfield eBay
Pros: Two-way bookshelf design with a 1” tweeter and 6.5” woofer, part of Polk’s budget-friendly XT lineup (spanning roughly $200-700 across the series). Measures more linear and has fewer/smaller cabinet resonances than its smaller sibling, the XT15, making it - by the reviewer’s own assessment - probably the better of the two based on data alone. Reasonably good bass output for the price and size, with an F3 of 63Hz. Horizontal radiation of about ±50° gives a respectable, enjoyable soundstage width. Takes well to EQ correction - the early-reflections directivity trend is decently linear, meaning tonal adjustments can meaningfully improve the sound. Provides usable, respectable volume when paired with a subwoofer crossover, even though it isn’t intended to play extremely loud on its own. Measured bass extension of 64.5Hz (-3dB), with a measured sensitivity of 86dB.
Cons: Notably bright treble, elevated roughly 1-5dB above the midrange depending on frequency - a characteristic shared across the whole Polk XT lineup, requiring either EQ or toe-out to tame. Small resonances appear around 300Hz and 800Hz, with some of that energy leaking from the port area. Vertical listening window is narrow - best kept close to the tweeter axis, with only a couple of degrees of tolerance above or below before the sound changes. Still needs a subwoofer for real low-end extension despite the decent F3. Overall linearity isn’t state-of-the-art flat, and while the reviewer found it pleasant, some artificial brightness remains even after basic EQ correction in the crossover region.
Full Polk Monitor XT20 review and specifications →
| Bass Extension (-10dB) | 43.4Hz (derived, log-interpolated between spinorama.org -9dB/-12dB points) |
|---|---|
| Bass Extension (-3dB) | 64.5Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 13”H x 7.5”W x 11”D (330.2 x 190.5 x 279.4 mm) |
| Drivers | 6.5” bilaminate paper cone woofer, 1” Terylene dome tweeter |
| Impedance | 8 ohms nominal (measured, Erin’s Audio Corner) |
| Sensitivity | 86dB (measured by Erin’s Audio Corner; 87dB manufacturer specified) |
| Spinorama Preference Score | 4.71 |
| Spinorama Preference Score with Perfect Sub | 7.07 |
| Weight | 11.9 lbs (5.4 kg) each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: Polk’s new budget XT Speakers. Reviewed! More from Erin’s Audio Corner →
- Erin’s Audio Corner Website Polk Monitor XT20
- Erin’s Audio Corner: 10 Great (and Terrible) Speakers Under $300!
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- Erin’s Audio Corner Measurements (spinorama.org)
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