Short answer: both are discontinued, so this only matters if you are buying used. Used, the Rythmik FV25HP is the better pick: it ranks #23 of 143 subwoofers by sound quality (rated 4.4/5), against #141 (rated 3.3/5) for the BK Electronics Monolith-DF. If you want one new, the JTR Speakers Orbit Shifter PRO ranks #1 at $4,499.
The Rythmik FV25HP is the better-sounding pick. 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.
The case for the BK Electronics Monolith-DF: A down ported 12 inch subwoofer with balanced XLR and RCA inputs at a low price, now discontinued. The catch: Deep-bass output is more limited than the strong 40-80 Hz result suggests, so it is not the right choice when the lowest movie effects are the priority.
Buy the Rythmik FV25HP 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.
Looking for alternatives? See the complete Subwoofers rankings.
A tall dual 15 inch ported subwoofer with strong, deep bass for big rooms and both balanced and RCA inputs.
A down ported 12 inch subwoofer with balanced XLR and RCA inputs at a low price, 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
| Rythmik FV25HP | BK Electronics Monolith-DF | |
|---|---|---|
| Price | $2,499 Discontinued | £406.95 Discontinued |
| Ranked | #23 of 143 in Large Home Subwoofers (Over 75 lbs) | #141 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | ported, bottom |
| Output SPL at 10 Hz | 99.7 dB | - |
| Output SPL at 12.5 Hz | 108.4 dB | - |
| Output SPL at 15 Hz | 113.2 dB | 91.3 dB |
| Output SPL at 20 Hz | 116.6 dB | 102.0 dB |
| Output SPL at 25 Hz | 119.1 dB | 106.4 dB |
| Output SPL at 31.5 Hz | 122.4 dB | 108.3 dB |
| Output SPL at 40 Hz | 124.7 dB | 108.6 dB |
| Output SPL at 50 Hz | 126.1 dB | 108.7 dB |
| Output SPL at 63 Hz | 126.7 dB | 108.6 dB |
| Output SPL at 80 Hz | 127.3 dB | 107.7 dB |
| Output SPL at 100 Hz | 127.9 dB | - |
| Output SPL at 125 Hz | 127.8 dB | - |
| CEA-2010-A Average (40-80Hz) | 126.2 dB | 108.4 dB |
| Dimensions | 41.5”H x 21”W x 22”D (1054.1 x 533.4 x 558.8 mm) | 23.8”H x 21.3”W x 16.5”D (603.8 x 539.8 x 419.9 mm) |
| Weight | 210.1 lbs (95.3 kg) | 103.2 lbs (46.8 kg) |
| Warranty | 5/3 | 2 |
| Cabinet Color | black | black, wood |
| Country | United States | United Kingdom |
| Measurement Source | Data-bass | Ilkka Rissanen |
| Drivers | 2x 15” (381mm) driver | 12” (305mm) driver with ported design |
| Inputs | XLR (2), RCA (line/LFE) | XLR (balanced), RCA (unbalanced) |
| 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 |
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