Short answer: both are discontinued, so this only matters if you are buying used. Used, the Power Sound Audio (PSA) TRIAX is the better pick: it ranks #5 of 143 subwoofers by sound quality (rated 4.5/5), against #88 (rated 4.1/5) for the Monoprice Monolith M15-S. If you want one new, the JTR Speakers Orbit Shifter PRO ranks #1 at $4,499.
Buy the Power Sound Audio (PSA) TRIAX 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.
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
| Monoprice Monolith M15-S | Power Sound Audio (PSA) TRIAX | |
|---|---|---|
| Price | $999 Discontinued | $7,995 Discontinued |
| Ranked | #88 of 143 in Large Home Subwoofers (Over 75 lbs) | #5 of 143 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | sealed | sealed |
| Output SPL at 15 Hz | 100.1 dB | - |
| Output SPL at 20 Hz | 105.6 dB | 119.8 dB |
| Output SPL at 25 Hz | 111.2 dB | 119.8 dB |
| Output SPL at 31.5 Hz | 115.2 dB | 119.8 dB |
| Output SPL at 40 Hz | 118.4 dB | 130.9 dB |
| Output SPL at 50 Hz | 119.3 dB | 130.9 dB |
| Output SPL at 63 Hz | 119.6 dB | 130.9 dB |
| Output SPL at 80 Hz | 118.9 dB | - |
| Output SPL at 100 Hz | 119.1 dB | - |
| Output SPL at 125 Hz | 118.9 dB | - |
| CEA-2010-A Average (40-80Hz) | 119.0 dB | 130.9 dB (avg of 3/4 bands) |
| Dimensions | 23.5”H x 16.7”W x 19.7”D (596.9 x 424.2 x 500.4 mm) | 23.5”H x 31”W x 27.5”D (596.9 x 787.4 x 698.5 mm) |
| Warranty | 5 | 5 |
| Country | United States | United States |
| Measurement Source | Manufacturer | Manufacturer |
| Weight | 80 lbs (36.3 kg) | 229.9 lbs (104.3 kg) |
| Drivers | 15” (381mm) driver | 3x 15” (381mm) driver |
| Inputs | - | XLR (balanced, with loop output) |
| XLR Input | - | Yes |
| RCA Input | - | No |
| 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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