Short answer: the Monoprice Monolith 16 THX Ultra. It ranks #18 of 110 subwoofers by sound quality at $2300; the Power Sound Audio (PSA) S3600i ranks #29 and costs $5995, so there is not much of a tradeoff to weigh.
What the Monoprice Monolith 16 THX Ultra offers: 16-inch ported driver and THX Ultra certification deliver 126.5dB CEA-2010-A average at a fraction of the price of the subwoofers ranked above it. Watch for: Heavy at 78 kg and ported design can interact with room acoustics.
What the Power Sound Audio (PSA) S3600i offers: Independent CEA-2010 testing records 104.7 dB at 20 Hz and 125.0 dB through 40-80 Hz. The sealed enclosure with 2x 18” (457mm) driver delivers formidable upper-bass output for movie effects and music. Watch for: 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. The 609.6H x 711.2W x 508.0D mm cabinet and 62.1 kg mass still require deliberate placement and calibration.
Buy the Monoprice Monolith 16 THX Ultra. It ranks higher for sound quality than the Power Sound Audio (PSA) S3600i and costs less, so there is no real case for the other one.
Looking for alternatives? See the complete Subwoofers rankings.
Specifications Side By Side
| Monoprice Monolith 16 THX Ultra | Power Sound Audio (PSA) S3600i | |
|---|---|---|
| Price | $2,300 | $5995 |
| Ranked | #18 of 110 in Large Home Subwoofers (Over 75 lbs) | #29 of 110 in Large Home Subwoofers (Over 75 lbs) |
| Enclosure | ported, front | sealed |
| Output SPL at 15 Hz | 107.3 dB | 101.1 dB |
| Output SPL at 20 Hz | 118.4 dB | 104.7 dB |
| Output SPL at 25 Hz | 123.3 dB | 107.9 dB |
| Output SPL at 31.5 Hz | 125.1 dB | 113.6 dB |
| Output SPL at 40 Hz | 126.3 dB | 119.9 dB |
| Output SPL at 50 Hz | 126.5 dB | 125.8 dB |
| Output SPL at 63 Hz | 126.6 dB | 127.4 dB |
| Output SPL at 80 Hz | 126.8 dB | 126.9 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 | 125.0 dB |
| Dimensions | 25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm) | 24"H x 28"W x 20"D (609.6 x 711.2 x 508.0 mm) |
| Weight | 171.5 lbs (77.8 kg) | 136.9 lbs (62.1 kg) |
| Warranty | 5 | 5 |
| Cabinet Color | black | - |
| Country | United States | United States |
| Measurement Source | Audioholics | Brent Butterworth |
| Drivers | 16" (406mm) driver | 2x 18" (457mm) driver |
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Prices on this page were last checked September 14, 2026 at 1:47 AM 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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The Two Speakers In Full
Monoprice Monolith 16 THX Ultra: $2,300 eBay
Pros: 16-inch ported driver and THX Ultra certification deliver 126.5dB CEA-2010-A average at a fraction of the price of the subwoofers ranked above it.
Cons: Heavy at 78 kg and ported design can interact with room acoustics.
Notes: Product # 42031
Full Monoprice Monolith 16 THX Ultra review and specifications →
| CEA-2010-A Average (40-80Hz) | 126.5 dB |
|---|---|
| Cabinet Color | black |
| Country | United States |
| Dimensions | 25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm) |
| Drivers | 16" (406mm) driver |
| Enclosure | ported, front |
| Measurement Source | Audioholics |
| Output SPL at 15 Hz | 107.3 dB |
| Output SPL at 20 Hz | 118.4 dB |
| Output SPL at 25 Hz | 123.3 dB |
| Output SPL at 31.5 Hz | 125.1 dB |
| Output SPL at 40 Hz | 126.3 dB |
| Output SPL at 50 Hz | 126.5 dB |
| Output SPL at 63 Hz | 126.6 dB |
| Output SPL at 80 Hz | 126.8 dB |
| Output SPL at 100 Hz | 127.2 dB |
| Output SPL at 125 Hz | 127.6 dB |
| Warranty | 5 |
| Weight | 171.5 lbs (77.8 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by Audioholics; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons
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Power Sound Audio (PSA) S3600i: $5995 eBay
Pros: Independent CEA-2010 testing records 104.7 dB at 20 Hz and 125.0 dB through 40-80 Hz. The sealed enclosure with 2x 18” (457mm) driver delivers formidable upper-bass output for movie effects and music.
Cons: 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. The 609.6H x 711.2W x 508.0D mm cabinet and 62.1 kg mass still require deliberate placement and calibration.
Full Power Sound Audio (PSA) S3600i review and specifications →
| CEA-2010-A Average (40-80Hz) | 125.0 dB |
|---|---|
| Country | United States |
| Dimensions | 24"H x 28"W x 20"D (609.6 x 711.2 x 508.0 mm) |
| Drivers | 2x 18" (457mm) driver |
| Enclosure | sealed |
| Measurement Source | Brent Butterworth |
| Output SPL at 15 Hz | 101.1 dB |
| Output SPL at 20 Hz | 104.7 dB |
| Output SPL at 25 Hz | 107.9 dB |
| Output SPL at 31.5 Hz | 113.6 dB |
| Output SPL at 40 Hz | 119.9 dB |
| Output SPL at 50 Hz | 125.8 dB |
| Output SPL at 63 Hz | 127.4 dB |
| Output SPL at 80 Hz | 126.9 dB |
| Warranty | 5 |
| Weight | 136.9 lbs (62.1 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by Brent Butterworth; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons