Amplifiers & Separates

Monoprice Monolith M8125X and M8250X Class D Amplifiers Released!

A while ago, Monoprice announced a pair of 8-channel ATI designed and built Class D amps featuring the Hxpex N-Core amplifiers at their heart. The Monoprice Monolith M8125X, priced at $2000, and the M8250X at $3000 are both Class D amplifiers. The M8125X has eight channels and is rated 100 watts per channel while the M8250X is rated 200 watts into its eight channels. They’ve now been released! Let’s take a closer look.

Tons of Power and Channels, XLR Connections Only

Aside from pricing and model numbers, we don’t know much about these new amplifiers. We know that they use the Hypex N-Core Class D amplifiers with switch-mode power supplies. The M125X has a single 20 amp inlet. The M250X has TWO 20 amp inlets! These are beefy amps! The N-Core design also maintains a very linear output with all but the most esoteric speakers.

Monoprice Monolith 8125X Back
Monoprice Monolith M8250X Back

Clearly, Monoprice is targeting a specific consumer with the Monolith M8125X and M8250X Class D amplifiers. You can tell because of the lack of RCA inputs. The XLR input-only configuration will limit their audience, as most consumer-grade AV receivers forego balanced XLR in favor of space-saving RCA outputs. While you could use an RCA to XLR cable, there are more accessible and less expensive amplifiers that feature both. Plus, if you use an RCA to XLR cable, it negates any benefits of balanced XLR in the first place. Of course, Monoprice’s HTP-1 16-channel Processor has XLR outputs. This is a clear suggestion from them that these amps should be used with it. Now, if you are thinking that 8+8=16, remember that three of those XLR outputs on the HTP-1 are for subwoofers. You’d have three unused channels if you used two of these new amps.

We also know that ATI continues to manufacture the Monolith Amplifiers for Monoprice. ATI has been in the game for 30+ years and is one of the most reputable amplifier producers. Rest assured, your Monolith amplifier will last a very long time.


Both the Monolith M8125X and M8200X feature a 3RU rack-mountable design. Both also maintain the clean and sleek look favoured by Monoprice. A simple black finish, with a convenient (and simple) power button and minimal badging, adds to the Monolith design aesthetic. As the ‘90s rack system guy, I still dig that aesthetic.

Monoprice has neatly laid out the back end with the XLR connections up top and the speaker outputs underneath. A 12v trigger, grounding lug, the master power switch, and some user-replaceable fuses are to the right. At the bottom is the power connections.

The Monolith M8125X and M8200X get passive cooling thanks to an oversized heatsink. Passive cooling means no noisy fans heard during quiet scenes. Class D amps have always been notoriously cool compared to their brother and sister A/B amps. And while Audiophiles will claim that A/B are superior in sound, having owned both, the only thing that A/B excels at is heating your room.

Our Take 

The new M8125X and M8250X Monoprice Class D amplifiers certainly look as if they will be continuing the Monolith namesake for being large and powerful. Providing more than enough power in either variant, these new Class D amps, built by ATI, can power anything you throw at it. I am puzzled by the decision to exclude RCA inputs. You can order these now from Monoprice. Let us know how you like them in the comments!

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