Short answer: the Andover Audio SpinSub. It ranks #30 of 48 subwoofers by sound quality, rated 3.3/5, at $350; the Monoprice Monolith 8 THX Certified ranks #43, rated 2.7/5, at $350. The price gap is small enough that the sound-quality ranking should decide it.
What the Andover Audio SpinSub does well: Independent CEA-2010 testing records 107.4 dB through 40-80 Hz. The catch: Without a published 20 Hz output result, deep-bass capability is less certain than its midbass figure.
What the Monoprice Monolith 8 THX Certified does well: A compact 9kg, ported 8-inch subwoofer with THX certification that can suit a small room or satellite-based system without taking much floor space. Watch for: Deep-bass output is modest for a home-theater subwoofer, falling to 72.9dB at 20Hz and 86.1dB at 25Hz.
One note: the Andover Audio SpinSub is discontinued and no longer widely available new.
Buy the Andover Audio SpinSub. It is rated higher for sound quality than the Monoprice Monolith 8 THX Certified at the same price, so it is the default pick unless a specific strength of the other one matters more to you.
Still deciding? The full Subwoofers rankings cover every ranked option.
Specifications Side By Side
| Andover Audio SpinSub | Monoprice Monolith 8 THX Certified | |
|---|---|---|
| Price | $350 Discontinued | $350 Discontinued |
| Ranked | #30 of 48 in Small Home Subwoofers (Under 30 lbs) | #43 of 48 in Small Home Subwoofers (Under 30 lbs) |
| Enclosure | ported | ported |
| Output SPL at 25 Hz | 91.2 dB | 86.1 dB |
| Output SPL at 31.5 Hz | 98.6 dB | 93.2 dB |
| Output SPL at 40 Hz | 104.3 dB | 96.9 dB |
| Output SPL at 50 Hz | 105.5 dB | 99.3 dB |
| Output SPL at 63 Hz | 110.3 dB | 100.7 dB |
| Output SPL at 80 Hz | 109.6 dB | 101.6 dB |
| CEA-2010-A Average (40-80Hz) | 107.4 dB | 99.6 dB |
| Dimensions | 14.2”H x 11.3”W x 12.7”D (361.9 x 285.8 x 323.8 mm) | 12.6”H x 13.5”W x 12.6”D (319.8 x 342.9 x 319.8 mm) |
| Weight | 20.9 lbs (9.5 kg) | 19.8 lbs (9.0 kg) |
| Cabinet Color | black, grey | black |
| Country | United States | United States |
| Measurement Source | Brent Butterworth | ErinsAudioCorner |
| Drivers | 2x 6.5” (165mm) driver | 8” (203mm) driver |
| Output SPL at 20 Hz | - | 72.9 dB |
| Output SPL at 100 Hz | - | 101.9 dB |
Related Speaker Comparisons
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- Paradigm Millenia CT vs Monoprice Monolith 8 THX Certified
- Monoprice Premium Select 8in 200-Watt vs Monoprice Monolith 8 THX Certified
- Dayton Audio SUB-1000L vs Monoprice Monolith 8 THX Certified
Prices on this page were last checked September 29, 2026 at 3:43 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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The Two Speakers In Full
Andover Audio SpinSub: $350 Discontinued eBay
Pros: Independent CEA-2010 testing records 107.4 dB through 40-80 Hz. The ported enclosure with 2x 6.5” (165mm) driver is intended to add useful bass support without a full-size cabinet.
Cons: Without a published 20 Hz output result, deep-bass capability is less certain than its midbass figure. The 361.9H x 285.8W x 323.8D mm cabinet and 9.5 kg mass still need careful placement and calibration. Discontinued.
Full Andover Audio SpinSub review and specifications →
| CEA-2010-A Average (40-80Hz) | 107.4 dB |
|---|---|
| Cabinet Color | black, grey |
| Country | United States |
| Dimensions | 14.2”H x 11.3”W x 12.7”D (361.9 x 285.8 x 323.8 mm) |
| Drivers | 2x 6.5” (165mm) driver |
| Enclosure | ported |
| Measurement Source | Brent Butterworth |
| Output SPL at 25 Hz | 91.2 dB |
| Output SPL at 31.5 Hz | 98.6 dB |
| Output SPL at 40 Hz | 104.3 dB |
| Output SPL at 50 Hz | 105.5 dB |
| Output SPL at 63 Hz | 110.3 dB |
| Output SPL at 80 Hz | 109.6 dB |
| Weight | 20.9 lbs (9.5 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
Monoprice Monolith 8 THX Certified: $350 Discontinued eBay
Pros: A compact 9kg, ported 8-inch subwoofer with THX certification that can suit a small room or satellite-based system without taking much floor space. Measured output is useful through the upper bass: 99.3dB at 50Hz, 100.7dB at 63Hz and 101.6dB at 80Hz. Its selectable THX/EQ modes provide a more controlled option for music than the extended setting.
Cons: Deep-bass output is modest for a home-theater subwoofer, falling to 72.9dB at 20Hz and 86.1dB at 25Hz. It will not deliver the infrasonic impact or room-filling output of a larger model, and the manufacturer lists it as out of stock. Choose it for compactness and moderate listening levels, not for demanding cinema effects. Discontinued.
Notes: Product # 41289
Full Monoprice Monolith 8 THX Certified review and specifications →
| CEA-2010-A Average (40-80Hz) | 99.6 dB |
|---|---|
| Cabinet Color | black |
| Country | United States |
| Dimensions | 12.6”H x 13.5”W x 12.6”D (319.8 x 342.9 x 319.8 mm) |
| Drivers | 8” (203mm) driver |
| Enclosure | ported |
| Measurement Source | ErinsAudioCorner |
| Output SPL at 20 Hz | 72.9 dB |
| Output SPL at 25 Hz | 86.1 dB |
| Output SPL at 31.5 Hz | 93.2 dB |
| Output SPL at 40 Hz | 96.9 dB |
| Output SPL at 50 Hz | 99.3 dB |
| Output SPL at 63 Hz | 100.7 dB |
| Output SPL at 80 Hz | 101.6 dB |
| Output SPL at 100 Hz | 101.9 dB |
| Weight | 19.8 lbs (9.0 kg) |
- Links
- Reviews, Comparisons and Sound Samples
- Independently measured by ErinsAudioCorner; the published figures above come from this ASR subwoofer measurement thread.
- Head-to-Head Comparisons