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Monoprice Unveils 3 Affordable Monolith Class A/B Power Amplifiers For Your Home Theater

Monoprice’s latest Monolith Series power amplifiers offer an affordable path for those looking to improve the sound quality of their home theater system.

Monoprice Monolith M5100X Amplifier Front

Monoprice has started to build a real following in the home theater category with its range of loudspeakers, subwoofers, and power amplifiers. The Monoprice Monolith Series has continued to grow over the past two years and keeping their products affordable has certainly helped.

In 2022, they added two high-end 8-channel Class D power amplifiers, the 8125X and 8250X which are ideal for Dolby Atmos and DTS:X home theater systems.

For 2023, Monoprice is offering up three moderately priced Monolith power amplifiers, the M2100X (2 channels), M3100X (three channels), and M3100X (5 channels). These provide more options for different setup configurations. 

Monoprice Monolith M5100X Amplifier Rear
Monoprice Monolith M5100X (5 channel)
Monoprice Monolith M3100X Amplifier Rear
Monoprice Monolith M3100X (3 channel)
Monoprice Monolith M2100X Amplifier Rear
Monoprice Monolith M2100X (2 channel)

These amps are not only designed to complement Monolith speakers, but other loudspeakers you may have or are considering.

What a Power Amplifier Is

The purpose of a power amplifier is to supply power and transfer audio signals to one or more speakers. However, It doesn’t have the extra features and connections you often find on a home theater receiver, such as a radio, input source switching, and audio/video (AV) processing. The only control you typically find on a power amplifier (apart from a power switch) is a primary gain control, which is analogous to volume. 

Tip: Mononprice Monolith power amplifiers don’t have a gain control. That function is left up to a connected preamp or AV preamp/processor. 

Power amplifiers come in a variety of channel configurations, from a single channel (aka Monoblock) that powers just one speaker, two-channel (stereo), or multi-channel (typically 3, 5, or 7 channels) for home theater applications. 

However, to use a power amplifier, a separate preamp or AV preamp/processor is required to get audio signals from content sources to the power amplifier.

For example, an AV preamp/processor decodes or processes audio source signals and passes the signals to the power amp, which, in turn, sends the signals to the speakers. The signals are passed in analog form via line outputs using RCA-type connections or, in some higher-end preamp/power amplifier combinations, XLR connections.

Monoprice Monolith M3100X Amplifier Internal

Features in Common

Tip: The rest of this article refers to more technical information. Check on the provided links for more details on what they mean. Another source that will help is Understanding Amplifier Power Output Specifications

  • Amplifier Type: Class A/B
  • Input Connection Options: RCA, XLR
  • Power Output (Full Bandwidth @ 8 Ohms): 90 Watts per channel
  • Power Output (Full Bandwidth @ 4 Ohms): 135 Watts per channel
  • Tip: Speaker Load Impedance Safe from 4 to 16 ohms
  • EIA 1kHz Output Power at 8 Ohms: 155 Watts
  • Total Harmonic Distortion (THD): A Weighted < 0.02%
  • Frequency Response: 20Hz to 20Khz
  • Signal to Noise Ratio (SNR): A Weighted >100dB
  • Gain Range: RCA Input 28.5dB
  • Gain Range: XLR Input 28dB
  • Damping: >500
  • Input Impedance: 27 kOhms
  • Speaker Connections: 5-Way Binding Posts
  • Trigger Input:: 6 – 12 V (AC or DC); <10 mA input current required
  • Trigger Output: 12 VDC; can drive any load up to 120 mA
  • Dimensions (all three power amps): 21×5 x19.5 x 9.0-inches (545 x 490 x 230 mm)


Power Amp ModelM2100XM3100XM5100X
Number of Channels235
Net Weight29.5 lbs/13.4 kg32.4 lbs/14.7 kg35.5 lbs/16.1 kg

Price & Availability

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  1. J. Allen

    August 5, 2023 at 11:55 am

    So far everything I have purchased that has the Monoprice label on it has been a disappointment.

    • Ian White

      August 5, 2023 at 12:00 pm

      Can you be more specific because I’ve purchased 3 things from them that have been rather great for the money.


      Ian White

      • James

        August 6, 2023 at 9:57 pm

        Not just for the money, they beat out some higher prices brands on features and build quality

  2. Dave

    August 6, 2023 at 2:10 am

    I would expect a 2/3 channel to have more power than those but I have 2 of the monolith 12s and they have been fantastic. I just ordered the OSD 3 channel so I’m hoping those work out well for me.

    • James

      August 6, 2023 at 9:58 pm

      Just be aware, the XLRs on these new models are unbalanced so you get the same feature as an unbalanced RCA.

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