Musical Fidelity M5Si: A successor to the Nu-Vista 800 flagship amplifier

The Musical Fidelity M5si integrated amplifier is the first and only representative of the new M5s line. In terms of ideology, design and main indicators, it is closer to the Musical Fidelity M6si than to the budget Musical Fidelity M3si . And although this model does not use nuvistors, the company positions it as a successor to the flagship Nu-Vista 800. We will consider engineering solutions a little later, but for now we will simply evaluate the appearance and build quality. The design is absolutely typical for Musical Fidelity, with an extremely free front panel, on which there is nothing but a few buttons and a large volume control. Elegant engraving on the nameplate made of stainless medical steel subtly emphasizes the laconicism of the style. Durable powder coating withstands fairly harsh handling without losing its marketable appearance.

The functionality of the Musical Fidelity M5si amplifier can be easily assessed by examining it from the back. The input switch is designed for five inputs – four linear and Phono for MM heads. I note that Musical Fidelity phono preamplifiers, even inexpensive ones, have always been designed very competently. One of the linear inputs, Aux 1, is switched to Home Theater mode by a slide switch, and in this case the signal is fed directly to the power amplifier, and adjustments are made in the AV processor. External control is also provided by a 12-volt trigger, and through, with an output. There are two linear outputs – fixed and adjustable, which makes it possible to expand the system architecture. But the main feature of the M5si, of course, is the DAC with an asynchronous USB input, receiving a signal up to 24/96. Not record parameters for our times, but still better than 44/16 and quite sufficient for familiarization with digital audio. And finally, the acoustic terminals are isolated WBT, meeting safety requirements. The output power of the amplifier is 2 x 150 W at 8-ohm load, and this is a very solid indicator.

The channels are assembled on a common printed circuit board, but are powered by different transformer windings and their own rectifiers with smoothing capacitors of 10,000 μF x 80 V. The positive and negative buses, wide and short, are also divided by channels. This is the right decision, providing increased dynamics and better transient attenuation. In the output stages, powerful transistors are paralleled in the shoulder in pairs, which allows for an increased current to be delivered to the load. The circuit has a relay protection that switches off the acoustics when a constant voltage appears at the amplifier output.

The weak point of most powerful amplifiers is the ability to convey sound nuances at a normal, comfortable volume. There is even a term “the problem of the first watt.” So we decided to check whether the Musical Fidelity M5si is subject to subtle matters, having selected acoustics with a neutral character and high sound resolution – the ProAc DB1 shelf monitors.

I should immediately note that the amplifier heats up quite a bit: hot air comes out through the ventilation grid on the right side of the top cover due to convection. This means that the output stage does not operate in a very “deep” class AB, as one might expect with such a declared power. And the problem of the first watt is impossible to notice by ear. There is no loss of resolution on complex fragments, all the richness of timbres and the naturalness of the transition from quiet sounds to loud ones are preserved. There is no feeling of a failure of space at low volume – the scene is drawn in detail and on a large scale. These qualities are most fully manifested in classical music with a large dynamic range. Here the ability of the amplifier to show its dynamic potential is already evident. The most powerful tutti without compression and coloration at power peaks, solid energy with an accentuated impact even when working with shelf acoustics in combination with a comfortable delivery of quiet fragments. Of course, rock is also presented very emotionally, it’s just that classical music is usually recorded better, and in the interpretation of Musical Fidelity M5si makes an unusually strong impression.

Specifications Musical Fidelity M5Si

Output power: 2 x 150 W (8 Ohm)
THD + noise: <0.010% (20 Hz – 20 kHz
Signal-to-noise ratio (A-weighted): >100 dB
Frequency range: 10 Hz – 20 kHz (+0, -0.1 dB)
Analog inputs: 4 x RCA linear, phono MM
Digital input: USB B (in asynchronous mode up to 24 bit / 96 kHz
Control: trigger input and output (3.5 mm)
Analog outputs: fixed, adjustable
Dimensions (W x H x D): 440 x 100 x 405 mm
Weight: (net / gross): 14.6 / 18.8 kg