Short answer: both are discontinued, and they are rated the same for sound quality (#19 and #23 of 143 subwoofers). Either one is only an option used, so choose on condition and price.
What the Monoprice Monolith 16 THX Ultra does well: A THX Ultra certified 16 inch ported subwoofer with huge output for far less money than most rivals, now worth finding used. Watch for: Heavy at 172 lbs (78 kg) and ported design can interact with room acoustics.
The case for the Rythmik FV25HP: A tall dual 15 inch ported subwoofer with strong, deep bass for big rooms and both balanced and RCA inputs. Watch for: The 1054.1H x 533.4W x 558.8D mm cabinet and 210.1 lbs (95.3 kg) mass make this a serious placement and moving commitment.
Buy the Monoprice Monolith 16 THX Ultra or the Rythmik FV25HP, whichever you find used in better condition; both are discontinued.
Still deciding? The full Subwoofers rankings cover every ranked option.
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 15 inch ported subwoofer with strong, deep bass for big rooms and both balanced and RCA inputs.
Prices on this page were last checked October 29, 2026 at 4:42 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 | Rythmik FV25HP | |
|---|---|---|
| Price | $2,300 Discontinued | $2,499 Discontinued |
| Ranked | #19 of 143 in Large Home Subwoofers (Over 75 lbs) | #23 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | ported, front |
| Output SPL at 15 Hz | 107.3 dB | 113.2 dB |
| Output SPL at 20 Hz | 118.4 dB | 116.6 dB |
| Output SPL at 25 Hz | 123.3 dB | 119.1 dB |
| Output SPL at 31.5 Hz | 125.1 dB | 122.4 dB |
| Output SPL at 40 Hz | 126.3 dB | 124.7 dB |
| Output SPL at 50 Hz | 126.5 dB | 126.1 dB |
| Output SPL at 63 Hz | 126.6 dB | 126.7 dB |
| Output SPL at 80 Hz | 126.8 dB | 127.3 dB |
| Output SPL at 100 Hz | 127.2 dB | 127.9 dB |
| Output SPL at 125 Hz | 127.6 dB | 127.8 dB |
| CEA-2010-A Average (40-80Hz) | 126.5 dB | 126.2 dB |
| Dimensions | 25.6”H x 22”W x 28.1”D (650.2 x 558.8 x 713.7 mm) | 41.5”H x 21”W x 22”D (1054.1 x 533.4 x 558.8 mm) |
| Weight | 171.5 lbs (77.8 kg) | 210.1 lbs (95.3 kg) |
| Warranty | 5 | 5/3 |
| Cabinet Color | black | black |
| Country | United States | United States |
| Measurement Source | Audioholics | Data-bass |
| Drivers | 16” (406mm) driver | 2x 15” (381mm) driver |
| Inputs | XLR, RCA, XLR out | XLR (2), RCA (line/LFE) |
| XLR Input | Yes | Yes |
| RCA Input | Yes | Yes |
| TRS Input | No | No |
| Optical Input | No | No |
| Coaxial Input | No | No |
| USB Input | No | No |
| HDMI Input | No | No |
| AES Input | No | No |
| Aux Input | No | No |
| Output SPL at 10 Hz | - | 99.7 dB |
| Output SPL at 12.5 Hz | - | 108.4 dB |
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