Musical Fidelity M6si500 Dual Mono Integrated Amplifier - Black

Two Monoblocks and a Preamp, in One Case

The Musical Fidelity M6si500 is an integrated amplifier only in the sense that it lives in one box. Inside are a separate preamp stage and two independent monoblock power amps, each with its own large toroidal transformer feeding it. The preamp sits above them on its own level.

That layout is why the numbers look the way they do. Power is 500 watts per channel into 8 ohms. There is no shared supply for the two channels to fight over, so what one channel is doing has no effect on the other.

What 500 Watts Buys You

It is not really about volume. A speaker that dips low in impedance asks for current, and most amplifiers start to strain when it does. This one does not, which is why it holds its shape on dense music where a smaller amp turns the bottom end to mush.

Built Like the Price Suggests

The front panel is milled from a single extrusion of military-grade aluminum, and the heatsinks are made specially rather than bought in. The whole thing weighs 30kg, or 66 pounds, and measures 440 by 160 by 460mm. It needs a shelf that means it.

The Bench Numbers

Distortion plus noise stays under 0.01% across the audio band, and signal-to-noise is better than 100dB A-weighted. Frequency response runs from 10Hz to 20kHz within a tenth of a decibel. Those are the figures of a well-sorted power amplifier, not a compromise.

Connections are deliberately plain. Four line-level RCA inputs, one of them switchable to home theater bypass, and one balanced XLR input. On the way out there is a preamp output and a fixed-level output. Nothing else is in the signal path.

What Reviewers Are Saying

Doug Schroeder reviewed this amplifier for Dagogo, under its earlier M6 500i name. His verdict on power was unambiguous: it "has power on reserve to drive nearly any speaker you care to use."

What he valued was that the reserve was never audible as effort. "I never felt the music lacked punch or weight," he wrote, having enjoyed "the crispness of the M6 500i" on bass-heavy material.

Who Is This Amplifier Best For?

• Your speakers are hard to drive — 500 watts a channel from two independent monoblocks means the amplifier stops being the reason a difficult pair sounds flat.
• You want separates without the separates — a preamp and two monoblocks in one chassis saves two boxes, two power cords and a pair of interconnects, and the shelf space they need.
• You already own a home theater — one line input switches to bypass, so a processor can drive the front channels and the same amplifier serves both systems.
• You want it to last — a machined aluminum front, custom heatsinks and 66 pounds of build are what you are paying for as much as the watts.
• The M6si500 is a pure analog amplifier — there is no converter, no phono stage and no streaming on board, so digital sources need something ahead of it. Add one from our DACs.

How Does It Connect to Your System?

Four line-level RCA inputs take a CD player, a converter, a phono stage or a streamer, and a balanced XLR input takes a source with balanced outputs. One of the RCA inputs can be set to home theater bypass for an AV processor.

Speaker cable goes to the binding posts. A preamp output and a fixed-level output are on the back for a subwoofer or a recorder, and the amplifier is happy driving long cable runs given the supply behind it.

Pairs Well With

Building your system? Here are some great companions:

• Speakers: 500 watts a channel deserves a serious pair — see our Floorstanding Speakers.
• DAC: The digital front end this amplifier leaves to you — browse our DACs.
• Cables: Balanced or single-ended into the amp, and good cable out — see our Speaker Cables.
• Audio Rack: At 66 pounds it needs a shelf built for it — see our Audio Racks.

Frequently Asked Questions

How much power does it deliver?

500 watts per channel into 8 ohms, which Musical Fidelity quotes as 27dBW.

What does dual mono actually mean here?

Two independent monoblock power amps, each with its own toroidal transformer, plus a separate preamp stage above them.

Which inputs does it have?

Four line-level RCA inputs, one of which can be set to home theater bypass, and one balanced XLR input.

Does it have a built-in DAC or phono stage?

It is a pure analog amplifier. A converter or phono stage connects to one of the line inputs.

How big and heavy is it?

440 by 160 by 460mm, weighing 30kg, or about 66 pounds.

What are the measured figures?

Distortion plus noise below 0.01%, signal-to-noise better than 100dB A-weighted, and response within 0.1dB from 10Hz to 20kHz.

See It in Action

HIghFIdelity Stereo runs the amplifier with a pair of PMC Twenty26:

And Phil Ear takes a closer look at the same amplifier:

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Learn More

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