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 Reserve R100 ranks #160, rated 3.4/5, and costs $699, so there is little reason to consider the other one.
The Ascend Acoustics CBM-170 SE2 is the more accurate option. 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 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 bookshelf speakers with unusually useful bass for their size and a vent that avoids port noise. 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.
Prices on this page were last checked November 7, 2026 at 7:34 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.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| Ascend Acoustics CBM-170 SE2 | Polk Reserve R100 | |
|---|---|---|
| Price | $468 per pair | $699.00 per pair |
| Ranked | #113 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 |
Related Speaker Comparisons
How Ascend Acoustics CBM-170 SE2 compares with other leading options: