Musical Fidelity M5si
In the early days, British amplifier manufacturers were renowned for building low-powered amplifiers. Exceptionally high-quality low-powered amplifiers, but low-powered all the same. It was their penchant for doing this that provided US amplifier manufacturers with their first footholds in the audio industry, because the Americans became equally renowned for building high-quality high-power amplifiers. So if you wanted a low-powered amp you bought British, and if you wanted a high-powered amp you bought American.
One person who never bought into this paradigm was Antony Michaelson, who founded Musical Fidelity in the UK in 1982 and is still its sole owner and managing director. His first power amplifier, the strangely named Dr Thomas, was rated at 120W per channel, his second (the A370) at 185W per channel, and he later went on to build the Titan, rated at 1000W per channel into 8 ohms and able to deliver 4000W into 2 ohms!
Musical Fidelity’s new M5si isn’t in the Titan’s power league, but with a rating of 150W continuous per channel into 8 ohms, it falls midway between Dr Thomas and the A370… at least in terms of power output.
Musical Fidelity M5si
Musical Fidelity is also renowned for changing the appearance of its products, so there’s no real ‘signature style’ to which the M5si could conform. We liked the company’s ‘cylindrical’ period, during which time almost all its products were built in tubular form, but the M5si’s comfortingly rectangular shape is far more practical… and unlike some previous models, it’s also tastefully classy, with its large volume knob and badging contrasting nicely with the black of the front panel (silver is the other finish available). 
The front-panel controls are also very tastefully done: small push-buttons with tiny blue tell-tale LEDs above to show circuit status, the exception being the STBY button, which has two LEDs — blue for ‘On’ and orange for ‘Standby’. From left to right, the input buttons are CD, USB, Phono, Tuner, Aux1/HT and Aux2. What looks to be a button at the far right is, in reality, an IR receiver ‘window’ that’s been bulged outwards to enable the remote control to be used from a wider area in front of the amplifier. 
The USB input is to take the feed from a computer, supporting up to 24/96. The ‘HT’ input allows you to bypass the M5si’s volume control so you can integrate it into a home theatre set-up by using the M5si for high-quality power to drive the front-channel speakers.
The remote supplied with the M5si is a multi-function type that can also be used to control Musical Fidelity’s five CD players, ranging from the M3CD player right up to the Nu-Vista Reference CD player, and because of this the remote has many more buttons than are required to operate the M5si, but very sensibly grouped, so the buttons that control the M5si are in one area and coloured blue — you can’t confuse them with the other buttons, which are grey-coloured. The remote is plastic and not particularly pretty, but the buttons for the amp are all easily reached with a single thumb. It’s powered by two AAA batteries, and Musical Fidelity includes two high-quality Panasonic-branded alkaline cells, which is to be commended because many manufacturers provide cheap, carbon-zinc ‘no-name’ batteries, which we always advise you to replace immediately (lest they leak and destroy your remote control).
The rear panel has just a single pair of multi-way loudspeaker terminals and, in addition to the inputs you’d expect to find, adds both line and pre-amplifier outputs as well as trigger inputs and outputs. 
Musical Fidelity M5si
The volume control of the Musical Fidelity M5si is motorised, but unlike many motorised remotes, it doesn’t ‘feel’ like one when you’re turning it manually. Plus there’s not the common backlash of a motorised control, so when you set it at a particular volume level manually, that level doesn’t go down slightly when you release the knob. There’s a slot etched into the knob so you can see what level it’s set at, though a small LED would have been more visible, especially from a distance.
The M5si’s muting circuit can only be activated via the remote control, and once muted, you need the remote to turn it off, because moving the volume control doesn’t do this (it should, really, but few do). Rest assured that if you mislay the remote while the amplifier is muted, you can de-mute the circuit by switching the amplifier to standby, then back on. In this case the amplifier will stay muted for seven seconds, after which it will de-mute. Whenever you switch the amplifier off, it will always reset to the same input source that was being used when you switched it off, and also to the same volume level.
Our listening sessions got off to a brilliant start because we started off with Sean McMahon and the Moonmen’s new album ‘Shiner’, (playing the title track before moving on to the opener ‘House of Mirrors’ because it sounds better this way). Gotta love the guitar riff on this track, and the M5si gave it the grunt it needed: raw, natural and with perfect timing. ‘Broken Hill’ allowed the M5si to prove how transparent it is reproducing male vocal, something many amps don’t do well because their designers have concentrated on the more popular female vocal range during their fine-tuning sessions. But the M5si shone with female vocal equally well, with us just soaking up the sound of Emily Lubitz’s gorgeously sensual tones on ‘Love is a Dog’ as well as her somewhat strained falsetto. We particularly loved the cello sound on the track ‘Diary’. The spare sound of this album also made it easy to appreciate how quiet Musical Fidelity has been able to make the M5si: the silence behind the music makes it stand out all the more.
The M5si was superb at allowing us to hear the fine details in music being played, and there’s plenty of detailing to be heard in Wild Feathers’ album ‘Lonely is a Lifetime’, whether it’s multitracked vocals (‘Overnight’), harmonised vocals (‘Don’t Ask Me to Change’), or sheer aural strangeness (‘Hallelujah’). With this new album, Wild Feathers has certainly changed its musical direction, with echoes of everyone from Bob Dylan to The Eagles via the Rolling Stones and Pink Floyd. This is one great album, and it sounded fabulous via the Musical Fidelity M5si.
When music sounds this good, the words ‘turn it up’ are the most used around here, and it was heard constantly during our audition time with the Musical Fidelity M5si. However, the amplifier was powerful enough that when we obliged by spinning the front panel control clockwise, or thumbing the ‘volume up’ button on the remote, we could just as easily get a call of ‘maybe not that loud!’ before we’d even started exploring the upper reaches of the amplifier’s power output capabilities.
This is a beautifully-engineered amplifier that combines great sound quality with high power output and ‘sultry’ looks that will integrate perfectly with any décor. Highly recommended.
Musical Fidelity M5si

Click for magazine PDFMusical Fidelity M5si stereo amplifier
Price: $3695

+ High power, Great sound, Sultry looks
- No auto standby option; No digital inputs other than USB

Power output: 150W per channel into 8 ohms
THD+N: <0.010% typical 20Hz–20kHz
S/N ratio: >100dB ‘A’-weighted
Frequency response: 10Hz to 20kHz  –0.1dB
Inputs: 4 × line level RCA, 1 × USB type ‘B’ connector, 1 × MM phono input
USB input: Asynchronous data up to 24-bit/96kHz
Phono input sensitivity: 3mV nominal (MM)
Phono input S/N ratio: >70dB ‘A’-weighted
Phono input impedance: 50kohms (MM)
RIAA response: 20Hz–20kHz ±0.5dB
Dimensions (whd): 400 × 100 × 405mm
Weight: 14.6kg
Warranty: Two years