Monoprice Monolith 16 THX Ultra vs Monoprice Monolith 15 THX Ultra

Last updated: September 16, 2026

Short answer: the Monoprice Monolith 16 THX Ultra if sound quality matters most, the Monoprice Monolith 15 THX Ultra if price matters most. The Monoprice Monolith 16 THX Ultra ranks #18 of 110 subwoofers at $2300. The Monoprice Monolith 15 THX Ultra ranks #59 at $1999, $301 cheaper.

Monoprice Monolith 16 THX Ultra vs Monoprice Monolith 15 THX Ultra

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 Monoprice Monolith 15 THX Ultra offers: Independent CEA-2010 testing records 110.0 dB at 20 Hz and 120.5 dB through 40-80 Hz. The ported, front enclosure with 15” (381mm) driver has the headroom for demanding film bass in a large room. Watch for: The 680.7H x 449.6W x 701.0D mm cabinet and 58.3 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 if sound quality is the priority over the price, or the Monoprice Monolith 15 THX Ultra if the price is the priority over sound quality.

Looking for alternatives? See the complete Subwoofers rankings.

Specifications Side By Side

Monoprice Monolith 16 THX Ultra Monoprice Monolith 15 THX Ultra
Price$2,300$1999
Ranked#18 of 110 in Large Home Subwoofers (Over 75 lbs)#59 of 110 in Large Home Subwoofers (Over 75 lbs)
Enclosureported, frontported, front
Output SPL at 15 Hz107.3 dB100.8 dB
Output SPL at 20 Hz118.4 dB110.0 dB
Output SPL at 25 Hz123.3 dB115.6 dB
Output SPL at 31.5 Hz125.1 dB118.0 dB
Output SPL at 40 Hz126.3 dB122.0 dB
Output SPL at 50 Hz126.5 dB121.0 dB
Output SPL at 63 Hz126.6 dB120.0 dB
Output SPL at 80 Hz126.8 dB119.0 dB
Output SPL at 100 Hz127.2 dB119.0 dB
Output SPL at 125 Hz127.6 dB118.0 dB
CEA-2010-A Average (40-80Hz)126.5 dB120.5 dB
Dimensions25.6"H x 22"W x 28.1"D (650.2 x 558.8 x 713.7 mm)26.8"H x 17.7"W x 27.6"D (680.7 x 449.6 x 701.0 mm)
Weight171.5 lbs (77.8 kg)128.5 lbs (58.3 kg)
Warranty55
Cabinet Colorblackblack
CountryUnited StatesUnited States
Measurement SourceAudioholicsErinsAudioCorner
Drivers16" (406mm) driver15" (381mm) driver
Output SPL at 12.5 Hz-90.0 dB

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

Prices on this page were last checked September 16, 2026 at 12:41 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 →

Monoprice Monolith 15 THX Ultra: $1999 eBay

Monoprice Monolith 15 THX Ultra ranking card

Pros: Independent CEA-2010 testing records 110.0 dB at 20 Hz and 120.5 dB through 40-80 Hz. The ported, front enclosure with 15” (381mm) driver has the headroom for demanding film bass in a large room.

Cons: The 680.7H x 449.6W x 701.0D mm cabinet and 58.3 kg mass make this a serious placement and moving commitment. Ported output does not solve room modes, so careful placement and calibration remain essential.

Notes: Product # 24458

Full Monoprice Monolith 15 THX Ultra review and specifications →

CEA-2010-A Average (40-80Hz)120.5 dB
Cabinet Colorblack
CountryUnited States
Dimensions26.8"H x 17.7"W x 27.6"D (680.7 x 449.6 x 701.0 mm)
Drivers15" (381mm) driver
Enclosureported, front
Measurement SourceErinsAudioCorner
Output SPL at 12.5 Hz90.0 dB
Output SPL at 15 Hz100.8 dB
Output SPL at 20 Hz110.0 dB
Output SPL at 25 Hz115.6 dB
Output SPL at 31.5 Hz118.0 dB
Output SPL at 40 Hz122.0 dB
Output SPL at 50 Hz121.0 dB
Output SPL at 63 Hz120.0 dB
Output SPL at 80 Hz119.0 dB
Output SPL at 100 Hz119.0 dB
Output SPL at 125 Hz118.0 dB
Warranty5
Weight128.5 lbs (58.3 kg)
Search eBay for Monoprice Monolith 15 THX Ultra →