Short answer: both are discontinued, so this only matters if you are buying used, though neither ranks well in its class. Used, the Monoprice Monolith 8 THX Certified is the better pick: it ranks #66 of 73 subwoofers by sound quality (rated 2.7/5), against #69 (rated 2.6/5) for the Paradigm Millenia CT. Both are rated below 3.0/5 among the 73 subwoofers; for better sound, the Edifier T5s ranks #2 at $169.99.
The case for the Paradigm Millenia CT: A slim 8 inch subwoofer that adds bass support without the footprint of a full size cabinet. Watch for: 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 THX certified 8 inch subwoofer with selectable modes, sized for a small room or satellite system. The catch: Deep-bass output is modest for a home-theater subwoofer, falling to 72.9dB at 20Hz and 86.1dB at 25Hz.
Buy the Monoprice Monolith 8 THX Certified 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 Edifier T5s instead.
Want more options? Browse the full Subwoofers rankings.
A slim 8 inch subwoofer that adds bass support without the footprint of a full size cabinet.
A compact THX certified 8 inch subwoofer with selectable modes, sized for a small room or satellite system.
Prices on this page were last checked October 23, 2026 at 8:27 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.
As an eBay Partner, we may be compensated if you make a purchase.
Specifications Side By Side
| Paradigm Millenia CT | Monoprice Monolith 8 THX Certified | |
|---|---|---|
| Price | $499 Discontinued | $350 Discontinued |
| Ranked | #69 of 73 in Small Home Subwoofers (Under 30 lbs) | #66 of 73 in Small Home Subwoofers (Under 30 lbs) |
| Output SPL at 25 Hz | 67.8 dB | 86.1 dB |
| Output SPL at 31.5 Hz | 80.0 dB | 93.2 dB |
| Output SPL at 40 Hz | 90.4 dB | 96.9 dB |
| Output SPL at 50 Hz | 100.0 dB | 99.3 dB |
| Output SPL at 63 Hz | 106.7 dB | 100.7 dB |
| CEA-2010-A Average (40-80Hz) | 99.0 dB (avg of 3/4 bands) | 99.6 dB |
| Dimensions | 15.7”H x 5”W x 14”D (400.0 x 127.0 x 355.6 mm) | 12.6”H x 13.5”W x 12.6”D (319.8 x 342.9 x 319.8 mm) |
| Weight | 12.6 lbs (5.7 kg) | 19.8 lbs (9.0 kg) |
| Warranty | 3 | - |
| Country | Canada | United States |
| Measurement Source | Brent Butterworth | ErinsAudioCorner |
| Drivers | 8” (203mm) driver | 8” (203mm) driver |
| Enclosure | ported | ported |
| Output SPL at 20 Hz | - | 72.9 dB |
| Output SPL at 80 Hz | - | 101.6 dB |
| Output SPL at 100 Hz | - | 101.9 dB |
| Cabinet Color | - | black |
Related Speaker Comparisons
More worthwhile head-to-heads for Monoprice Monolith 8 THX Certified: