Monoprice Monolith M-215 vs Rythmik F18

Last updated: September 17, 2026

Short answer: the Monoprice Monolith M-215. It ranks #23 of 110 subwoofers by sound quality, rated 4.4/5, at $2999.99. The Rythmik F18 ranks #69, rated 4.1/5, at $2344, $655.99 cheaper, which does not close the gap in sound quality.

Monoprice Monolith M-215 vs Rythmik F18

Buy the Monoprice Monolith M-215. It is rated higher for sound quality, and saving $655.99 with the Rythmik F18 does not make up for the sound-quality gap.

Looking for alternatives? See the complete Subwoofers rankings.

Buy the Monoprice Monolith M-215 at Monoprice ($2999.99) →Buy the Rythmik F18 at Rythmik Audio ($2,344) →

Specifications Side By Side

Monoprice Monolith M-215 Rythmik F18
Price$2999.99$1,850
Ranked#23 of 110 in Large Home Subwoofers (Over 75 lbs)#69 of 110 in Large Home Subwoofers (Over 75 lbs)
Enclosureported, frontsealed
Output SPL at 12.5 Hz103.9 dB97.4 dB
Output SPL at 15 Hz113.1 dB102.0 dB
Output SPL at 20 Hz118.9 dB106.2 dB
Output SPL at 25 Hz122.6 dB110.9 dB
Output SPL at 31.5 Hz125.2 dB114.3 dB
Output SPL at 40 Hz126.4 dB117.1 dB
Output SPL at 50 Hz126.1 dB119.1 dB
Output SPL at 63 Hz125.6 dB120.5 dB
Output SPL at 80 Hz125.6 dB121.2 dB
Output SPL at 100 Hz125.7 dB121.4 dB
Output SPL at 125 Hz126.3 dB121.4 dB
CEA-2010-A Average (40-80Hz)125.9 dB119.5 dB
Dimensions42.3"H x 20"W x 27.6"D (1074.4 x 508.0 x 701.0 mm)20.5"H x 20.5"W x 21"D (520.7 x 520.7 x 533.4 mm)
Weight216.1 lbs (98.0 kg)115.1 lbs (52.2 kg)
Warranty55/3
Cabinet Colorblackblack
CountryUnited StatesUnited States
Measurement SourceBrent ButterworthData-bass
Drivers2x 15" (381mm) drivers18" (457mm) driver
Output SPL at 10 Hz-93.7 dB
Inputs-XLR (2), RCA (line/LFE)
XLR Input-Yes
RCA Input-Yes
TRS Input-No
Optical Input-No
Coaxial Input-No
USB Input-No
HDMI Input-No
AES Input-No
Aux Input-No
Buy the Monoprice Monolith M-215 at Monoprice ($2999.99) →Buy the Rythmik F18 at Rythmik Audio ($2,344) →

More worthwhile head-to-heads for Monoprice Monolith M-215:

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 M-215: $2999.99 Monoprice eBay

Monoprice Monolith M-215 ranking card

Pros: Independent CEA-2010 testing records 118.9 dB at 20 Hz and 125.9 dB through 40-80 Hz. The ported, front enclosure with 2x 15” (381mm) drivers has the headroom for demanding film bass in a large room.

Cons: The 1074.4H x 508.0W x 701.0D mm cabinet and 98.0 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 # 38543

Full Monoprice Monolith M-215 review and specifications →

CEA-2010-A Average (40-80Hz)125.9 dB
Cabinet Colorblack
CountryUnited States
Dimensions42.3"H x 20"W x 27.6"D (1074.4 x 508.0 x 701.0 mm)
Drivers2x 15" (381mm) drivers
Enclosureported, front
Measurement SourceBrent Butterworth
Output SPL at 12.5 Hz103.9 dB
Output SPL at 15 Hz113.1 dB
Output SPL at 20 Hz118.9 dB
Output SPL at 25 Hz122.6 dB
Output SPL at 31.5 Hz125.2 dB
Output SPL at 40 Hz126.4 dB
Output SPL at 50 Hz126.1 dB
Output SPL at 63 Hz125.6 dB
Output SPL at 80 Hz125.6 dB
Output SPL at 100 Hz125.7 dB
Output SPL at 125 Hz126.3 dB
Warranty5
Weight216.1 lbs (98.0 kg)
Check current price at Monoprice ($2999.99) →Search eBay for Monoprice Monolith M-215 →

Rythmik F18: $1,850 Rythmik Audio eBay

Rythmik F18 ranking card

Pros: Independent CEA-2010 testing records 106.2 dB at 20 Hz and 119.5 dB through 40-80 Hz. The sealed enclosure with 18” (457mm) driver has the headroom for demanding film bass in a large room.

Cons: The 520.7H x 520.7W x 533.4D mm cabinet and 52.2 kg mass make this a serious placement and moving commitment. A sealed cabinet still needs careful placement and calibration to avoid room-mode peaks.

Full Rythmik F18 review and specifications →

AES InputNo
Aux InputNo
CEA-2010-A Average (40-80Hz)119.5 dB
Cabinet Colorblack
Coaxial InputNo
CountryUnited States
Dimensions20.5"H x 20.5"W x 21"D (520.7 x 520.7 x 533.4 mm)
Drivers18" (457mm) driver
Enclosuresealed
HDMI InputNo
InputsXLR (2), RCA (line/LFE)
Measurement SourceData-bass
Optical InputNo
Output SPL at 10 Hz93.7 dB
Output SPL at 12.5 Hz97.4 dB
Output SPL at 15 Hz102.0 dB
Output SPL at 20 Hz106.2 dB
Output SPL at 25 Hz110.9 dB
Output SPL at 31.5 Hz114.3 dB
Output SPL at 40 Hz117.1 dB
Output SPL at 50 Hz119.1 dB
Output SPL at 63 Hz120.5 dB
Output SPL at 80 Hz121.2 dB
Output SPL at 100 Hz121.4 dB
Output SPL at 125 Hz121.4 dB
RCA InputYes
TRS InputNo
USB InputNo
Warranty5/3
Weight115.1 lbs (52.2 kg)
XLR InputYes
Check current price at Rythmik Audio ($2,344) →Search eBay for Rythmik F18 →