MartinLogan Motion XT B100 vs Polk Reserve R100
The MartinLogan Motion XT B100 is more sensitive (93 dB vs 86 dB), so it plays louder per watt and plays lower (45 Hz vs 58 Hz). The Polk Reserve R100 is an easier load for a receiver (8 Ω vs 4 Ω) and costs less ($699 vs $850).
What each one works with
Checked against every product in our catalogue by the same engine as the compatibility checker.
| Motion XT B100 | Reserve R100 | |
|---|---|---|
| Receivers and amps that drive it | 28 of 29, 14 after a setting change | 29 of 29 |
Specs side by side
Values that differ are bold. A dash means that model doesn't publish the spec.
| Motion XT B100 | Reserve R100 | |
|---|---|---|
| Impedance | 4 Ω | 8 Ω |
| Sensitivity | 93 dB | 86 dB (2.83 V, 1 m) |
| Low end | 45 Hz | 58 Hz |
| Drivers | 1 × 32 mm, 1 × 165 mm | 1 × 25 mm, 1 × 133 mm |
| Size | 8×14×13 in | 6×13×10 in |
| Recommended amplifier power | 20–250 W | 30–150 W |
| Weight | 9.3 kg (20.5 lb) | 5.5 kg (12.1 lb) |
| MSRP | $850 each (MSRP, September 2026) | $699 a pair (MSRP, September 2026) |
Every spec and pairing: MartinLogan Motion XT B100, Polk Reserve R100.
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References
- MartinLogan Motion XT B100: Spec sheet, martinlogan.com, retrieved September 15, 2026
- MartinLogan Motion XT B100: Retailer listing, audioadvice.com, retrieved September 15, 2026
- Polk Reserve R100: Owner's manual, polkaudio.com, retrieved September 15, 2026
- Polk Reserve R100: Manufacturer product page, polkaudio.com, retrieved September 15, 2026
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