Monoprice Monolith 16 THX Ultra vs Paradigm Defiance X15

Last updated: September 14, 2026

Short answer: the Monoprice Monolith 16 THX Ultra if sound quality matters most, the Paradigm Defiance X15 if price matters most. The Monoprice Monolith 16 THX Ultra ranks #18 of 110 subwoofers at $2300. The Paradigm Defiance X15 ranks #38 at $1606.77, $693.23 cheaper.

Monoprice Monolith 16 THX Ultra vs Paradigm Defiance X15

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 Paradigm Defiance X15 offers: Independent CEA-2010 testing records 109.2 dB at 20 Hz and 122.9 dB through 40-80 Hz. The ported, bottom enclosure with 15” (381mm) driver has the headroom for demanding film bass in a large room. Watch for: The 625.3H x 588.8W x 625.3D mm cabinet and 41.7 kg mass make this a serious placement and moving commitment. Ported output does not solve room modes, so careful placement and calibration remain essential.

Buy the Monoprice Monolith 16 THX Ultra when sound quality outweighs the price for you, and the Paradigm Defiance X15 when the price outweighs sound quality instead.

Still deciding? The full Subwoofers rankings cover every ranked option.

Specifications Side By Side

Monoprice Monolith 16 THX Ultra Paradigm Defiance X15
Price$2,300$1,606.77
Ranked#18 of 110 in Large Home Subwoofers (Over 75 lbs)#38 of 110 in Large Home Subwoofers (Over 75 lbs)
Enclosureported, frontported, bottom
Output SPL at 15 Hz107.3 dB102.8 dB
Output SPL at 20 Hz118.4 dB109.2 dB
Output SPL at 25 Hz123.3 dB112.2 dB
Output SPL at 31.5 Hz125.1 dB116.2 dB
Output SPL at 40 Hz126.3 dB121.3 dB
Output SPL at 50 Hz126.5 dB123.4 dB
Output SPL at 63 Hz126.6 dB123.8 dB
Output SPL at 80 Hz126.8 dB123.1 dB
Output SPL at 100 Hz127.2 dB121.9 dB
Output SPL at 125 Hz127.6 dB121.2 dB
CEA-2010-A Average (40-80Hz)126.5 dB122.9 dB
Dimensions25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm)24.6"H x 23.2"W x 24.6"D (625.3 x 588.8 x 625.3 mm)
Weight171.5 lbs (77.8 kg)91.9 lbs (41.7 kg)
Warranty53
Cabinet Colorblackblack
CountryUnited StatesCanada
Measurement SourceAudioholicsAudioholics
Drivers16" (406mm) driver15" (381mm) driver

More worthwhile head-to-heads for Monoprice Monolith 16 THX Ultra:

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

Monoprice Monolith 16 THX Ultra ranking card

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 Colorblack
CountryUnited States
Dimensions25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm)
Drivers16" (406mm) driver
Enclosureported, front
Measurement SourceAudioholics
Output SPL at 15 Hz107.3 dB
Output SPL at 20 Hz118.4 dB
Output SPL at 25 Hz123.3 dB
Output SPL at 31.5 Hz125.1 dB
Output SPL at 40 Hz126.3 dB
Output SPL at 50 Hz126.5 dB
Output SPL at 63 Hz126.6 dB
Output SPL at 80 Hz126.8 dB
Output SPL at 100 Hz127.2 dB
Output SPL at 125 Hz127.6 dB
Warranty5
Weight171.5 lbs (77.8 kg)
Search eBay for Monoprice Monolith 16 THX Ultra →

Paradigm Defiance X15: $1,606.77 eBay

Paradigm Defiance X15 ranking card

Pros: Independent CEA-2010 testing records 109.2 dB at 20 Hz and 122.9 dB through 40-80 Hz. The ported, bottom enclosure with 15” (381mm) driver has the headroom for demanding film bass in a large room.

Cons: The 625.3H x 588.8W x 625.3D mm cabinet and 41.7 kg mass make this a serious placement and moving commitment. Ported output does not solve room modes, so careful placement and calibration remain essential.

Full Paradigm Defiance X15 review and specifications →

CEA-2010-A Average (40-80Hz)122.9 dB
Cabinet Colorblack
CountryCanada
Dimensions24.6"H x 23.2"W x 24.6"D (625.3 x 588.8 x 625.3 mm)
Drivers15" (381mm) driver
Enclosureported, bottom
Measurement SourceAudioholics
Output SPL at 15 Hz102.8 dB
Output SPL at 20 Hz109.2 dB
Output SPL at 25 Hz112.2 dB
Output SPL at 31.5 Hz116.2 dB
Output SPL at 40 Hz121.3 dB
Output SPL at 50 Hz123.4 dB
Output SPL at 63 Hz123.8 dB
Output SPL at 80 Hz123.1 dB
Output SPL at 100 Hz121.9 dB
Output SPL at 125 Hz121.2 dB
Warranty3
Weight91.9 lbs (41.7 kg)
Search eBay for Paradigm Defiance X15 →