Short answer: the Ascend Acoustics CBM-170 SE2. It ranks #113 of 222 bookshelf speakers by sound quality, rated 3.8/5, at $468. The Polk Monitor XT20 ranks #157, rated 3.4/5, at $277.50, $190.50 cheaper, not enough of a saving to outweigh the sound-quality gap.
The Ascend Acoustics CBM-170 SE2 is the more accurate pick. Compact two-way bookshelf speakers with a SEAS tweeter, a very flat midrange and smooth sound that suits most rooms. Its measured preference score, a predictor of how neutral it sounds, is 6.30 against 4.71 for the Polk Monitor XT20. The tradeoff: 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: Budget bookshelf speakers with good bass for their size and a fairly wide soundstage. 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 Acoustics CBM-170 SE2. It is rated higher for sound quality, and the $190.50 saving on the Polk Monitor XT20 is not enough to make up the difference.
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Specifications Side By Side
| Ascend Acoustics CBM-170 SE2 | Polk Monitor XT20 | |
|---|---|---|
| Price | $468 per pair | $277.50 per pair |
| Ranked | #113 of 222 in Large Size Bookshelf Speakers | #157 of 222 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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