Short answer: both are discontinued, so this only matters if you are buying used. Used, the Monoprice Monolith 16 THX Ultra is the better pick: it ranks #19 of 143 subwoofers by sound quality (rated 4.4/5), against #68 (rated 4.2/5) for the Monoprice Monolith M-212.
Why pick the Monoprice Monolith 16 THX Ultra: A THX Ultra certified 16 inch ported subwoofer with huge output for far less money than most rivals, now worth finding used. The tradeoff: Heavy at 172 lbs (78 kg) and ported design can interact with room acoustics.
Why pick the Monoprice Monolith M-212: A tall dual 12 inch ported subwoofer with deep, powerful bass for large rooms at a good price used. The tradeoff: The 924.6H x 449.6W x 599.4D mm cabinet and 174.2 lbs (79.0 kg) mass make this a serious placement and moving commitment.
Buy the Monoprice Monolith 16 THX Ultra only if you find one used in good condition; both are discontinued, and it is the better rated of the two.
Want more options? Browse the full Subwoofers rankings.
A THX Ultra certified 16 inch ported subwoofer with huge output for far less money than most rivals, now worth finding used.
A tall dual 12 inch ported subwoofer with deep, powerful bass for large rooms at a good price used.
Prices on this page were last checked October 31, 2026 at 7:11 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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Specifications Side By Side
| Monoprice Monolith 16 THX Ultra | Monoprice Monolith M-212 | |
|---|---|---|
| Price | $2,300 Discontinued | $1,620 Discontinued |
| Ranked | #19 of 143 in Large Home Subwoofers (Over 75 lbs) | #68 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | ported, front |
| Output SPL at 15 Hz | 107.3 dB | 104.2 dB |
| Output SPL at 20 Hz | 118.4 dB | 110.3 dB |
| Output SPL at 25 Hz | 123.3 dB | 114.5 dB |
| Output SPL at 31.5 Hz | 125.1 dB | 116.9 dB |
| Output SPL at 40 Hz | 126.3 dB | 119.7 dB |
| Output SPL at 50 Hz | 126.5 dB | 119.8 dB |
| Output SPL at 63 Hz | 126.6 dB | 120.3 dB |
| Output SPL at 80 Hz | 126.8 dB | 121.7 dB |
| Output SPL at 100 Hz | 127.2 dB | 121.5 dB |
| Output SPL at 125 Hz | 127.6 dB | 122.3 dB |
| CEA-2010-A Average (40-80Hz) | 126.5 dB | 120.4 dB |
| Dimensions | 25.6”H x 22”W x 28.1”D (650.2 x 558.8 x 713.7 mm) | 36.4”H x 17.7”W x 23.6”D (924.6 x 449.6 x 599.4 mm) |
| Weight | 171.5 lbs (77.8 kg) | 174.2 lbs (79.0 kg) |
| Warranty | 5 | 5 |
| Cabinet Color | black | black |
| Country | United States | United States |
| Measurement Source | Audioholics | Manufacturer |
| Drivers | 16” (406mm) driver | 2x 12” (305mm) drivers |
| Inputs | XLR, RCA, XLR 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 | - |
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