Short answer: both are discontinued, so this only matters if you are buying used. Used, the Monoprice Monolith M15-S is the better pick: it ranks #88 of 212 subwoofers by sound quality (rated 4.1/5), against #164 (rated 3.4/5) for the Emotiva X-Ref 12. If you want one new, the HSU Research VTF-3 MK5 HP ranks #59 at $1,049.
Buy the Monoprice Monolith M15-S only if you find one used in good condition; both are discontinued, and it is the better rated of the two. For a new speaker, start with the HSU Research VTF-3 MK5 HP instead.
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.
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Specifications Side By Side
| Emotiva X-Ref 12 | Monoprice Monolith M15-S | |
|---|---|---|
| Price | $999 Discontinued | $999 Discontinued |
| Ranked | #164 of 212 in Medium Home Subwoofers (30-75 lbs) | #88 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | sealed | sealed |
| Output SPL at 20 Hz | 84.0 dB | 105.6 dB |
| Output SPL at 25 Hz | 92.5 dB | 111.2 dB |
| Output SPL at 31.5 Hz | 102.1 dB | 115.2 dB |
| Output SPL at 40 Hz | 106.5 dB | 118.4 dB |
| Output SPL at 50 Hz | 110.6 dB | 119.3 dB |
| Output SPL at 63 Hz | 111.5 dB | 119.6 dB |
| Output SPL at 80 Hz | 110.7 dB | 118.9 dB |
| Output SPL at 100 Hz | 109.3 dB | 119.1 dB |
| Output SPL at 125 Hz | 108.1 dB | 118.9 dB |
| CEA-2010-A Average (40-80Hz) | 109.8 dB | 119.0 dB |
| Dimensions | 15.6”H x 14.6”W x 15.5”D (396.7 x 371.3 x 393.7 mm) | 23.5”H x 16.7”W x 19.7”D (596.9 x 424.2 x 500.4 mm) |
| Warranty | 5 | 5 |
| Country | United States | United States |
| Measurement Source | Audioholics | Manufacturer |
| Weight | 44.1 lbs (20.0 kg) | 80 lbs (36.3 kg) |
| Amplifier Power | 600W RMS | - |
| Frequency Response | 20-200Hz | - |
| Drivers | 12” (305mm) driver | 15” (381mm) driver |
| Inputs | XLR (balanced, with XLR daisy-chain output), RCA (stereo unbalanced) | - |
| 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 | - |
| Output SPL at 15 Hz | - | 100.1 dB |
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