Monoprice Monolith 16 THX Ultra vs Monoprice Monolith M15-S

Last updated: September 17, 2026

Short answer: the Monoprice Monolith 16 THX Ultra on measured sound quality, the Monoprice Monolith M15-S on price. The Monoprice Monolith 16 THX Ultra ranks #18 of 110 subwoofers, rated 4.4/5, at $2300. The Monoprice Monolith M15-S ranks #72, rated 4.1/5, at $999, $1301 cheaper.

Monoprice Monolith 16 THX Ultra vs Monoprice Monolith M15-S

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 (172 lbs) and ported design can interact with room acoustics.

Buy the Monoprice Monolith 16 THX Ultra if sound quality is the priority over the price, or the Monoprice Monolith M15-S if the price is the priority over sound quality.

Want more options? Browse the full Subwoofers rankings.

Specifications Side By Side

Monoprice Monolith 16 THX Ultra Monoprice Monolith M15-S
Price$2,300$999
Ranked#18 of 110 in Large Home Subwoofers (Over 75 lbs)#72 of 110 in Large 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"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 kg)80 lbs (36.3 kg)
Warranty55
Cabinet Colorblack-
CountryUnited StatesUnited States
Measurement SourceAudioholicsManufacturer
Drivers16" (406mm) driver15" (381mm) driver
InputsXLR, RCA, XLR out-
XLR InputYes-
RCA InputYes-
TRS InputNo-
Optical InputNo-
Coaxial InputNo-
USB InputNo-
HDMI InputNo-
AES InputNo-
Aux InputNo-

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

Prices on this page were last checked September 23, 2026 at 11:24 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

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 →

AES InputNo
Aux InputNo
CEA-2010-A Average (40-80Hz)126.5 dB
Cabinet Colorblack
Coaxial InputNo
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
HDMI InputNo
InputsXLR, RCA, XLR out
Measurement SourceAudioholics
Optical InputNo
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
RCA InputYes
TRS InputNo
USB InputNo
Warranty5
Weight171.5 lbs (77.8 kg)
XLR InputYes
Search eBay for Monoprice Monolith 16 THX Ultra →

Monoprice Monolith M15-S: $999 eBay

Monoprice Monolith M15-S ranking card

Pros: Published CEA-2010 specifications list 105.6 dB at 20 Hz and 119.0 dB through 40-80 Hz. The sealed enclosure with 15” (381mm) driver has the headroom for demanding film bass in a large room.

Cons: The 596.9H x 424.2W x 500.4D mm cabinet and 36.3 kg mass make this a serious placement and moving commitment. A sealed cabinet still needs careful placement and calibration to avoid room-mode peaks.

Notes: Product # 35141

Full Monoprice Monolith M15-S review and specifications →

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)
Search eBay for Monoprice Monolith M15-S →