Monoprice Monolith 16 THX Ultra vs Monoprice Monolith M15-S

Last updated: August 9, 2026

Short answer: the Monoprice Monolith 16 THX Ultra for the higher ranking, the Monoprice Monolith M15-S for the lower price. The Monoprice Monolith 16 THX Ultra ranks #13 of 97 subwoofers at $2300. The Monoprice Monolith M15-S ranks #62 at $999, $1301 cheaper.

The case for the Monoprice Monolith 16 THX Ultra: 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. The catch: Heavy at 78 kg and ported design can interact with room acoustics.

Buy the Monoprice Monolith 16 THX Ultra if the ranking matters more than the price. Buy the Monoprice Monolith M15-S if the price matters more than the ranking.

Specifications Side By Side

Monoprice Monolith 16 THX Ultra Monoprice Monolith M15-S
Price$2,300$999
Ranked#13 of 97 in Large Powered Home Subwoofers (Over 75 lbs)#62 of 97 in Large Powered Home Subwoofers (Over 75 lbs)
Enclosureported, frontsealed
Output SPL at 15 Hz107.3 dB100.1 dB
Output SPL at 20 Hz118.4 dB105.6 dB
Output SPL at 25 Hz123.3 dB111.2 dB
Output SPL at 31.5 Hz125.1 dB115.2 dB
Output SPL at 40 Hz126.3 dB118.4 dB
Output SPL at 50 Hz126.5 dB119.3 dB
Output SPL at 63 Hz126.6 dB119.6 dB
Output SPL at 80 Hz126.8 dB118.9 dB
Output SPL at 100 Hz127.2 dB119.1 dB
Output SPL at 125 Hz127.6 dB118.9 dB
CEA-2010-A Average (40-80Hz)126.5 dB119.0 dB
Dimensions25.6"H x 22.0"W x 28.1"D (650.2 x 558.8 x 713.7 mm)23.5"H x 16.7"W x 19.7"D (596.9 x 424.2 x 500.4 mm)
Weight171.5 lbs / 77.8 kg80 lbs / 36.3 kg
Warranty55
Cabinet Colorblack-
CountryUnited StatesUnited States
Measurement SourceAudioholicsManufacturer
Drivers16" (406mm) driver15" (381mm) driver

The Two Speakers In Full

Monoprice Monolith 16 THX Ultra: $2,300

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

CEA-2010-A Average (40-80Hz)126.5 dB
Cabinet Colorblack
CountryUnited States
Dimensions25.6"H x 22.0"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

Monoprice Monolith M15-S: $999

Monoprice Monolith M15-S ranking card

Notes: Product # 35141

CEA-2010-A Average (40-80Hz)119.0 dB
CountryUnited States
Dimensions23.5"H x 16.7"W x 19.7"D (596.9 x 424.2 x 500.4 mm)
Drivers15" (381mm) driver
Enclosuresealed
Measurement SourceManufacturer
Output SPL at 15 Hz100.1 dB
Output SPL at 20 Hz105.6 dB
Output SPL at 25 Hz111.2 dB
Output SPL at 31.5 Hz115.2 dB
Output SPL at 40 Hz118.4 dB
Output SPL at 50 Hz119.3 dB
Output SPL at 63 Hz119.6 dB
Output SPL at 80 Hz118.9 dB
Output SPL at 100 Hz119.1 dB
Output SPL at 125 Hz118.9 dB
Warranty5
Weight80 lbs / 36.3 kg

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Product prices and availability were last checked August 9, 2026 at 6:57 AM UTC 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.