Musical Fidelity, the UK-founded HiFi brand now under the same corporate ownership as turntable specialists Pro-ject Audio Systems, offers a full suite of gear from sources to speakers but is most well known for their amplifiers. Despite making waves in the last year with vintage-inspired product launches like the M1 Class A integrated amplifier and two BBC-style monitors, Musical Fidelity remains committed to their powerhouse Class A/B amplifier offerings. I had the privilege of spending quality time with their M3si integrated amplifier. Priced at USD 1599 the M3si sits one level above the entry-level M2 series. One step up from the base model—just how I spec my cars—this always seems to be a value sweet spot.

Affordable Class A/B amplifiers like the M3si are gradually becoming a legacy style product as streaming all-in-one amplifiers driven by Class D amplification are proliferating. What used to be the default amplification technology may soon become niche, much like manual transmission cars. How does the M3si stack up? It's the most affordable amplifier I’ve reviewed for Audiophilia and the only Class A/B integrated as well. Let’s see how this traditionally outfitted unit performed in my listening room.

Many thanks go out to Focal Naim, the US distributor of Musical Fidelity, for arranging the demo amplifier for this review. Logistics and communication are always smooth as butter with Focal Naim.

Features & Specifications

The M3si accepts analog RCA, MM phono and USB digital inputs and delivers a healthy 85 watts of music power per side. By comparison, its little sibling the M2si, includes only line inputs and offers slightly less power. The larger and more expensive M5si includes similar features to the M3si but its more advanced circuitry almost doubles the power output to 150 watts.

Despite its minimalist styling the M3si hosts a handful of practical features. I’d like to recognize the value of including preamplifier outputs, line outputs and home theatre (volume bypass) input. Any one of these is nice to have but all together they add a ton of flexibility for home theatre enthusiasts, subwoofer users or modular upgraders.

The one feature that dates the amp a bit is the single-input DAC. Several years ago, it made sense to include USB if a DAC was built into an integrated amplifier, but streamers are quickly replacing laptops as music servers even in entry-level audiophile systems. Coaxial and optical connections are more common for these sources.

The M3si does include a remote which is outdated, however, in use, I found no complaints. It’s just a minor cosmetic quibble that stands in contrast to the amplifier itself - which leads to thoughts on its design.

Before that, here are the complete specifications from Musical Fidelity:

Amplifier

Power output: 85 Watts per channel into 8 Ohms
THD(+ noise): <0.014 % typical, 20Hz to 20 kHz
Signal to Noise Ratio: >98dB ‘A’-weighted
Frequency Response: +0, –0.1dB, 10Hz to 20 kHz

Inputs

4x Line Level RCA / Phono
1x USB type ‘B’ connector - Asynchronous data stream at up to 24-bit/96kHz
1x MM Phono input

Phono Input

Sensitivity (nominal): 3mV (suitable for cartridges giving 1.5mV or more including high output MC types)
Signal / noise ratio: >70dB ‘A’-weighted
Input impedance: 50k Ohms
Frequency response: RIAA/IEC ±1dB, 20Hz to 20 kHz

General

Dimensions - WxHxD (mm): 440 x 100 x 400
Weight (unpacked/packed): 9.2 kg/ 13 kg

Design & Build

Industrial design is an area where the M3si stands out from its peers in the sub-$2000 price class. It is thoroughly clean, modern and thoughtfully laid out. It has a memorable face without any features that could be distracting. Just a handful of input selector buttons flank the massive volume knob in the center of the faceplate. Befitting its prominence, the volume knob is a pleasure to use, with satisfying resistance and control.

The Taiwan-assembled unit is constructed of a thick gauge steel chassis with a solid 5mm brushed aluminum faceplate. The fit and finish are wonderful throughout, especially considering the price point. I could not detect any hint of flex, creaking or play in the chassis or when using the connectors on the rear panel.

Overall the design of the M3si is perfectly aligned with its purpose: delivering music. While Musical Fidelity is not breaking new technological ground with this unit, the execution feels top-notch. I feel confident the M3si could stand up to a lifetime of wear and tear.

Daily Use & Setup

As expected for an integrated amplifier, the setup of the M3si was a plug-and-play exercise that took a minute or two.

Situated in my office reference system, I used the M3si for extensive dedicated listening as well as background music. It was also easy to integrate the M3si into my headphone system using the line level outputs.

The one feature that I did not use extensively was the USB DAC. Nice to have, but most of my casual and analytical listening is now done via a dedicated streamer or CD player which uses coaxial or optical outputs. Brief testing with my laptop revealed the DAC did indeed sound fine but I didn’t take detailed listening notes.

In daily operation, I was pleasantly surprised to find the M3si did not run particularly warm, which implied to me that it wasn’t wasting a ton of electricity. Generally not a deal breaker for hardcore audiophiles, but noteworthy.

Review System

Digital Sources: Wiim Mini Streamer, Ferrum ERCO DAC

Analog Sources: SOTA Escape Turntable & Ortofon 2M Blue Cartridge, Pro-ject Debut Carbon Turntable & Ortofon 2M Red Cartridge

Phono Preamplifiers: iFi ZenPhono, Parasound ZPhono

Amplification: Cambridge EVO 150, Aurorasound HFSA-01, Parasound HCA-750A

Loudspeakers: Canton Vento 20, PSB Synchrony B600, Care Orchestra Deep Breath Evo, Wharfedale Diamond 10.2

Analog Cables: Audio Art Classic Series

Listening

I spent extensive time spinning my beloved Grateful Dead Fillmore West 1969 February 28th box set (Rhino, 2019) while using the phono stage in the M3si. This is music I’ve listened to in one form or another going back to my iPod days. Even casual deadheads know the band could cover a lot of musical ground in a single night. There are plenty of cherished details from this set to look for in my listening: deep rumble from Phil Lesh’s bass, excessive rattle from the two drummers’ snares, Tom Constanten noodling on keys, and of course some of the best-stoned harmonies from the Dead’s late psychedelic period.

On tables using Ortofon 2M Red and 2M Blue cartridges, nicely priced to the M3si, I found the experience to be quite complete. There was the right blend of detail and insight without losing the rawness in the recording. Generally, I was pleased to find the built-in phono stage was just as quiet as my own Parasound ZPhono and iFi Zen Phono. In a price-appropriate system built around the M3si, it seemed an outboard phono stage could be a luxury reserved for exploring the more rarefied world of moving coil cartridges rather than a necessary upgrade.

Lately, I like to make sure my review listening includes electronic music and to scratch that itch I mine the digital catalogue of Ultimae Records of France for fresh ambient albums. Gems from artists like Aes Dana, Cell and Martin Nonstatic can be wonderful for both passive and focused listening. Live in Corfu from Cell (2020) features downtempo, spacey compositions that are nonetheless melodic. As far as sonic qualities the set features deep cavernous bass, expansive black backgrounds and clean synth lines and effects. The M3si leaned into this music in the best way and with a given speaker, could present the largest deepest soundstage of the amps in my stable. The bass response it could elicit from each speaker was prodigious in quantity and free of bloat.

Towards the end of my time with the M3si, saxophonist Joshua Redman released his first-ever album for Blue Note, Where Are We, featuring vocalist Gabrielle Cavassa. While familiar with Redman I had never heard of Cavassa and was intrigued by the partnership. This album was in near-constant streaming rotation until I returned the amplifier. Cavassa’s voice is warm, relaxed and very clean. In some ways, it’s the vocal equivalent of Redman’s tone from his sax. Never too much of a good thing, Redman and Cavassa together take the listener across the United States with a set of geographically themed standards and covers.

The M3si properly honoured this performance with each speaker I tried, helped in part by the album’s immaculate production quality. Given some of the M3si’s strengths, I see how it could handle midrange-focused vocal recordings. Listening to Where Are We reassured me the amplifier was not all brawn but had the brain (and heart) to do justice to a more tender recording.

With all the speakers I used, the M3si retained a consistent personality. It had massive drive, hard-hitting bass delivery, and the ability to command a wide clean soundstage. With warmer speakers the overall presentation was the most musical and with leaner speakers such as the Canton Vento 20, the presentation could turn brittle with recordings that were less than easy. While I only was able to try four different speakers, this trend was apparent enough for me to recommend that the M3si either be matched with neutral to warm speakers or carefully auditioned with unfamiliar speakers.

Conclusion

The Musical Fidelity M3si, while no spring chicken, justifies its long tenure in the brand's amplifier portfolio. Simple in design yet full of musical personality, it is a refreshing find in a segment where products often compete on features alone. With a bold delivery that belies its modest power specifications, its sonic performance is competitive at its $1599 MSRP. Thoughtful speaker matching will be required but this care will surely be rewarded with a powerful musical experience. I can warmly recommend the M3si and I am compelled to explore more products from Musical Fidelity in the future.

Further information: Musical Fidelity