Musical Fidelity M6si Review

Musical Fidelity M6si Review: It feels like déjà vu: I first tested the Musical Fidelity M6si back in 2023. At the time, Anthony Michaelson, the then-owner of Musical Fidelity (who recently sold the company to Heinz Lichtenegger of Pro-Ject), personally delivered the amplifier with great pride. He confidently claimed that there wouldn’t be a better integrated amplifier in the $2,500 class for a long time. Bold words, indeed. We put the M6si through rigorous testing, and by the end, we had to admit—it was unmatched in its price range at the time.

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Now, the M6si has crossed my path once again. This time, it’s at the heart of an impressive audio chain, paired with the Triangle Esprit Australe EZ floor-standing speakers, the Musical Fidelity M6scd CD player, and the Musical Fidelity M6sdac DAC. It’s a system that not only lives up to its reputation but exceeds it, proving that the M6si remains a force to be reckoned with.

So, after four years of running (and there’s no end in sight yet), we’re reassessing the current position: where is this musical Fidelity M6si today? It’s a big, heavy amplifier with a thick aluminum front and a sharp-looking (but smoothly rounded) heat sink on the side. The build quality is excellent, both inside and out.

It’s also selling well, not just within the MF/Triangle chain. Over the past four years, the M6si has become a benchmark in its class, even though it faces strong competition from its sibling, the M5si, which is £1,000 cheaper.

The M5si is two years newer, and since its excellent review with us in July 2022, it has been a constant favorite in our top picks. Still, the bigger M6si has a slight edge in features compared to the smaller M5si (it has one extra high-level input, and its phono stage can handle MC cartridges as well).

And the 2.0 kilos that it weighs more ( M5si = 14.6 kilos, M6si = 16.6 kilos) could also be due to the larger case.

The technology of the Musical Fidelity M6si

The M6si is designed as a “dual mono”, i.e., an amplifier whose left and right channels are completely separate.

It’s true down to the transformer: Anthony Michaelson only gave the M6si one, but it simulates a second one with its two taps. This is easily cheated because, of course, two separate transformers would be even better here. Still, the build is exceptional for the class.

The M6si delivers nearly 300 watts of power per channel at 4 ohms, thanks to two pairs of Sanken bipolar transistors (STD03N and STD03P) – the same setup used in the smaller M5si. Anthony Michaelson, the designer, has always been open about the similarities between the two amplifiers. The M6si’s higher power output comes from its more stable power supply.

Musical Fidelity M6si Features

The M6si is well-equipped but not overly flashy. It’s a solid integrated amplifier with a 24-bit/96 kHz USB input, which is common in amplifiers under €1,000. However, its phono input stands out, offering very low noise and excellent sound quality in both MM and MC modes.

I compared the M6si’s phono input to external phono stages costing between €300 and €400. While external phono stages often sound better, the M6si’s built-in phono input held its own, delivering higher dynamics and liveliness. I think it’s excellent.

Another useful feature is the home theater (HT) mode on one of the AUX inputs. This mode bypasses the volume control via a jumper on the back, making it easy to integrate the M6si into a multi-channel system where the AV receiver handles volume control.

The volume can be adjusted remotely, like most functions. Instead of a standard motorized potentiometer, the M6si uses the PGA2320, a high-quality, low-noise volume controller.

Musical Fidelity M6si in Practice

The M6si performs impressively. It handled every speaker I tested it with, even those with impedance dropping to 2 ohms. Its power and stability allow it to play at high volumes without issues. The sound is neutral, so it never felt mismatched with any speaker.

That said, some combinations work better than others. Reichmann Audio, the distributor, paired the M6si with Triangle speakers, and the result was outstanding. The Triangle Esprit Australe EZ, in particular, matched well with the M6si. The speaker’s lively character complemented the amplifier’s dynamic yet smooth sound. The combination delivered great expressiveness, deep and precise bass, natural soundstage, and high volume levels, making it my main choice for listening tests.

I also tested the M6si with other speakers, including the Dynaudio Contour 20, Magnat Signature 1109, and the reference Wolf from Langa Chicago. However, one thing to note is that the M6si gets quite warm near the power transformer. Stacking devices, like placing the M6scd CD player on top, isn’t ideal – it needs space for proper ventilation.

Listening Test

The listening test started with a comparison between the M6si and the smaller M5si. I was surprised by how the older M6si outperformed the M5si in our listening room.

The incredibly dynamic “Crying” from James Blood Ulmer’s album Live At Bayerischer Hof Munich sounded even more authentic, lively, and, above all, more rousing with the M6si. This amp doesn’t do a lot of shine, but it does almost everything right.

It hits the tone, keeps the bass very well under control, and has a very convincing basic tone. The balance between impressive dynamics and well-balanced naturalness is undoubtedly better than that of its little brother, the M5si. It is difficult to imagine that this difference is solely due to the higher performance.

With the M5si, the combination with the Triangle no longer sounded so natural and enchanting. Somehow, the kick was missing a bit. With the other loudspeakers – except for the Chicago – the livelier, more powerful, and more natural way of playing was no longer that important because, ultimately, the M5si is a great, very natural-sounding amplifier.

But the Chicago (which costs almost 40,000 euros), which, thanks to electromagnets in the low and mid-range and an open dipole housing, produces by far the most precise bass of all the loudspeakers tested at LowBeats so far, showed greater impulsiveness and greater naturalness in the playback of drums understand very well.

And, of course, it’s fun to unleash such a powerhouse as the Musical Fidelity M6si on a dynamic machine like the Von Langa Chicago. You’re always close to full-volume deflection…

Even the Exposure 3010 S2D, a superb, down-to-earth amplifier with a lot of energy and grip, didn’t have much to oppose the M6si’s unexcited liveliness.

The exposure on the Dynaudio was particularly good, but the M6si didn’t do badly with the Danish two-way box either, because it celebrated the voices so beautifully with it.

However, the M6si did not clear an amplifier hurdle: Our editorial favorite, the Atoll IN 300, did not let itself be overtaken by the Englishman as quickly as the other two class references.

The atoll mastered the powerful Cajon hits on Carlos Caceres Murga Argentina even faster, more springily, more “real” and even added a shovel of energy to James Blood Ulmer’s “Crying”.

The IN 300 tends to be minimally light and is, therefore, not necessarily the top partner for the Triangle. But on the Magnat or the Chicago, he made it sparkle a little more.

Pros and Cons of Musical Fidelity M6si Review

Pros:

Sound Quality: The Musical Fidelity M6si is known for its exceptional sound quality, offering high fidelity and clarity across the entire frequency range. It delivers detailed and precise audio reproduction, making it suitable for audiophiles and music enthusiasts.

Powerful Amplification: With a robust amplifier section, the M6si provides ample power to drive a wide range of speakers, including those with demanding impedance levels. This ensures clean and dynamic audio output even at higher volumes.

Versatile Connectivity: It features a variety of connectivity options, including multiple analog inputs (balanced and unbalanced), digital inputs (USB, coaxial, and optical), and a phono stage for vinyl enthusiasts. This versatility allows users to connect various audio sources without any hassle.

Build Quality: The M6si is well-built with high-quality components, ensuring durability and longevity. Its sturdy chassis helps minimize vibrations and interference, further enhancing the overall audio performance.

User-Friendly Design: It boasts a user-friendly design with intuitive controls and a clear display panel, making it easy to operate and navigate through different settings. Additionally, it comes with a remote control for convenient access to functions from a distance.

Cons:

Price: The M6si is relatively expensive compared to some other integrated amplifiers in its class. This might put it out of reach for budget-conscious buyers or those looking for more affordable options.

Size and Weight: It’s quite large and heavy, which could be a drawback for users with limited space or those who frequently need to move their audio equipment. Its substantial weight may also pose challenges during installation or setup.

Heat Dissipation: Like many high-powered amplifiers, the M6si can generate significant heat during operation. While adequate ventilation is provided, users need to ensure proper airflow to prevent overheating, especially when used in confined spaces or enclosed cabinets.

Limited Digital Features: While it offers digital inputs, some users may find the digital features of the M6si to be somewhat limited compared to dedicated digital audio components or streaming amplifiers. This might be a drawback for those seeking more advanced digital capabilities or network connectivity.

No Built-in Wireless Connectivity: Unlike some modern amplifiers, the M6si does not come with built-in Wi-Fi or Bluetooth connectivity. Users interested in wireless streaming would need to use external devices or accessories, adding to the overall cost and complexity of the setup.

Conclusion

One for all” was the motto of the three musketeers, and it perfectly suits the M6si, which stands as the ultimate symbol of what an integrated amplifier should be. Its build quality is impeccable, its design is rock-solid, and its performance is nothing short of extraordinary. With an abundance of power and a sound that’s both refined and commanding, the M6si pairs effortlessly with almost any speaker. But there’s one pairing that truly shines—the Triangle Esprit Australe EZ. Together, they create a match made in audio heaven, delivering a listening experience that’s nothing short of magical.

Though the M6si is little old, in the world of classic analog amplifier design, that’s merely a blink of an eye. It was a benchmark when it first arrived, and it remains so today. In its price range of 2,100 to 3,100, the M6si continues to set the standard, proving that true excellence stands the test of time. It’s not just an amplifier; it’s a masterpiece.

Musical Fidelity M6si Specification

Frequency Response: +0, –0.1dB, 10Hz to 20 kHz

Sensitivity: 3mV nominal (MM), 0.4mV nominal (MC)

Input impedance: 47k Ohms (MM and MC)

Frequency response: RIAA/IEC ±0.5dB 20Hz-20kHz

Dimensions – WxHxD (mm): 440 x 125 x 400

Weight: 16.6 kg/ 21.3 kg