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 #140 (rated 3.4/5) for the BK Electronics Extreme. If you want one new, the JTR Speakers Orbit Shifter PRO ranks #1 at $4,499.
The Monoprice Monolith 16 THX Ultra is the better-sounding choice. A THX Ultra certified 16 inch ported subwoofer with huge output for far less money than most rivals, now worth finding used. The catch: Heavy at 172 lbs (78 kg) and ported design can interact with room acoustics.
The case for the BK Electronics Extreme: A big 15 inch subwoofer with a powerful amplifier and continuous phase control for flexible setup, now discontinued. Watch for: It weighs 200.6 lbs (91 kg), which takes two or more people to move and needs a strong floor.
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. For a new speaker, start with the JTR Speakers Orbit Shifter PRO instead.
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 big 15 inch subwoofer with a powerful amplifier and continuous phase control for flexible setup, now discontinued.
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 | BK Electronics Extreme | |
|---|---|---|
| Price | $2,300 Discontinued | $5,995 Discontinued |
| Ranked | #19 of 143 in Large Home Subwoofers (Over 75 lbs) | #140 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | - |
| Output SPL at 15 Hz | 107.3 dB | 92.8 dB |
| Output SPL at 20 Hz | 118.4 dB | 100.7 dB |
| Output SPL at 25 Hz | 123.3 dB | 106.6 dB |
| Output SPL at 31.5 Hz | 125.1 dB | 110.7 dB |
| Output SPL at 40 Hz | 126.3 dB | 111.4 dB |
| Output SPL at 50 Hz | 126.5 dB | 111.1 dB |
| Output SPL at 63 Hz | 126.6 dB | 110.5 dB |
| Output SPL at 80 Hz | 126.8 dB | 109.0 dB |
| Output SPL at 100 Hz | 127.2 dB | - |
| Output SPL at 125 Hz | 127.6 dB | - |
| CEA-2010-A Average (40-80Hz) | 126.5 dB | 110.5 dB |
| Dimensions | 25.6”H x 22”W x 28.1”D (650.2 x 558.8 x 713.7 mm) | - |
| Weight | 171.5 lbs (77.8 kg) | 200.6 lbs (91 kg) |
| Warranty | 5 | - |
| Cabinet Color | black | - |
| Country | United States | United Kingdom |
| Measurement Source | Audioholics | Ilkka Rissanen |
| Drivers | 16” (406mm) driver | 15” (381mm) driver |
| 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 | - |
| Amplifier Power | - | 1000W RMS |
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