Short answer: the Monoprice Monolith M-10 V2 for extension, the Klipsch R-121SW for the lower price. The M-10 V2 is a 10-inch THX-certified ported sub with 500W RMS that reaches 17-20Hz, at $735.10. The R-121SW costs $389.99, and its 12-inch spun-copper driver with 200W RMS delivers controlled, musical bass with minimal distortion.
Buy the Klipsch R-121SW. It is rated higher for sound quality than the Monoprice Monolith M-10 V2 and costs less, so only choose the other one for a particular feature it does better.
Looking for alternatives? See the complete Subwoofers 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
| Klipsch R-121SW | Monoprice Monolith M-10 V2 | |
|---|---|---|
| Price | $389.99 | $735.10 |
| Ranked | #132 of 212 in Medium Home Subwoofers (30-75 lbs) | #161 of 212 in Medium Home Subwoofers (30-75 lbs) |
| Enclosure | ported, rear | ported, front |
| Output SPL at 15 Hz | 90.7 dB | 93.9 dB |
| Output SPL at 20 Hz | 96.0 dB | 104.8 dB |
| Output SPL at 25 Hz | 98.4 dB | 108.5 dB |
| Output SPL at 31.5 Hz | 102.3 dB | 109.3 dB |
| Output SPL at 40 Hz | 108.2 dB | 109.7 dB |
| Output SPL at 50 Hz | 112.4 dB | 110.1 dB |
| Output SPL at 63 Hz | 112.9 dB | 110.6 dB |
| Output SPL at 80 Hz | 111.3 dB | 110.9 dB |
| Output SPL at 100 Hz | 109.9 dB | 111.2 dB |
| Output SPL at 125 Hz | 108.3 dB | 111.5 dB |
| CEA-2010-A Average (40-80Hz) | 111.2 dB | 110.3 dB |
| Dimensions | 16.6”H x 16”W x 19.7”D (421.6 x 406.4 x 500.4 mm) | 20.9”H x 15”W x 18.9”D (530.9 x 381.0 x 480.1 mm) |
| Weight | 35.1 lbs (15.9 kg) | 72.5 lbs (32.9 kg) |
| Warranty | 5/2 | 5 |
| Cabinet Color | black | black |
| Country | United States | United States |
| Measurement Source | Audioholics | Manufacturer |
| Amplifier Power | 200W RMS | 500W RMS |
| Frequency Response | 28-120Hz | 17-20Hz |
| Drivers | 12” (305mm) driver | 10” (254mm) driver |
| Inputs | - | XLR, RCA, XLR passthrough out |
| XLR Input | - | Yes |
| RCA Input | - | Yes |
| TRS Input | - | No |
| Optical Input | - | No |
| Coaxial Input | - | No |
| USB Input | - | No |
| HDMI Input | - | No |
| AES Input | - | No |
| Aux Input | - | No |
Related Speaker Comparisons
More top alternatives to Klipsch R-121SW: