I recall that at some point in the dim and distant past Musical Fidelity founder Anthony Michaelson decided that the world needed educating about real world power requirements. To get this message across, he produced a cardboard calculator on which you dialled in the sensitivity of the loudspeaker next to the power output of your amplifier and this gave you a quality rating based on potential SPL (sound pressure level). Equating level with quality is a bit dubious but it did reveal that you need an awful lot of power to get high levels out of even a reasonably high sensitivity loudspeaker like the B&W 802D (listed on the back among other popular models). 200 Watts was required to get it into the ‘high quality’ zone and produce 106dB but to push it to the 110dB peak called for 500W. Which even today is a lot of power. It does explain however why Musical Fidelity has been building substantial integrated amplifiers since 1990 when the M8xi’s A1000 ancestor was released.
I imagine that it was nearly as heavy as the M8xi that takes its place in the company’s line up today as the biggest integrated in the catalogue. At 46kg the M8xi has the scale of a serious power amplifier and the specs to match; these are quoted as 550W into eight ohms and 870W into four with a peak offering of 1.2kW, so clearly ‘high quality’. But there is of course more to amplifier quality than sheer power; if it was that easy then the M8xi would probably be using Class D amps which deliver the most Watts per pound (sterling and avoirdupois) you can get.
A Class (AB) Act
Instead, the M8xi is very much a Class AB amplifier. Or should that be ‘amplifiers’, as this large but not excessive chassis houses a pair of monoblock power amplifiers and a preamplifier and each has its own transformer and power supply, hence the high mass. Each of the heat sinks that flank the chassis are dedicated to a channel and serve to keep a dozen bipolar transistors at a steady operating temperature, one that rises pretty high if the temperature on the outside is any indication. This is not like the legendary heat sinking atop a Musical Fidelity A1 Class A amp, which was hot enough to grill a burger. This is perhaps a reflection of the fact that this is a low feedback design with a Class A driver stage, but more likely because of the sheer quantity of power on offer.
The preamplifier circuitry has been placed right at the back of the box next to the input sockets, a move that keeps signal paths about as short as is possible. Inputs are both traditional analogue and contemporary digital, with the former in both balanced and single ended forms and the latter including USB and S/PDIF types in sufficient quantity to satisfy most system set-ups. Unusually, the Musical Fidelity has a wide range of outputs in both digital and analogue form; it seems unlikely that it would be used as a preamplifier but I guess it’s possible to bi-amp with a power amplifier if you have particularly insensitive speakers and a thirst for volume. Digital outputs can be used for a headphone amp/DAC of course, something that the M8xi doesn’t accommodate in its roster of features.
The DAC also has its own power supply, and while its hi-res figures are not particularly impressive (it maxes out at 24-bit/192kHz with no DSD or MQA support) they are at least realistic in the context of widely-available music files. All incoming data is upsampled and reclocked to reduce jitter.
Inputs are selected via a suitably large controller on the front panel or more often with the remote control, a rather heavily festooned example of the art that surprisingly does not offer up a power button. This it seems is one thing you can’t do from the sofa. It’s not hard to locate the volume buttons though, and I appreciated the fact that you can adjust level in half-decibel steps; steps that are reflected in the M8xi’s central display alongside the chosen input. I was a little surprised that it’s not possible to change the input names given the flexibility of the display, but this does mean that outside of the DAC there is little in the way of processing power onboard to corrupt the sound.
A Sense of Headroom
In the first instance I hooked this Musical Fidelity up to Bowers & Wilkins’ new 802 D4 loudspeakers, noting along the way that it has the lesser spotted C18 IEC power inlet and two sets of speaker terminals per channel for easy bi‑wiring. Initially I used the USB digital input on the amp and connected a Melco N10 streaming drive via Network Acoustics cable. London Grammar’s ‘Stay Awake’ revealed that those Watts count for something, producing a sense of headroom that you rarely encounter and which translates into prodigious bass when it’s on the recording, and on this one it certainly is. This is not bludgeoning power either, it’s articulate and able to respond to the nuances of the material with remarkable speed. High power and serious immediacy are not often found in combination even at this price yet the M8xi is very capable in both departments. Particularly with things like the synth powered vibes of Leifur James’ ‘Mumma Don’t Tell’ where the gradations in the bass come through superbly and the overall ease of delivery encourages you to push the volume.
Meshell Ndegeocello’s take on ‘Who Is He (And What Is He To You)?’ is underpinned by a dark chewy bass line that is positively sinuous in the M8xi’s hands, the tune flows with a powerful ease and the plushness of its production is brought to the fore. It brought to mind the possibly apocryphal story about Anthony Michaelson talking to Tim de Paravicini in the early days of Musical Fidelity where the latter is said to have scribbled down circuit details on the back of a cigarette packet, ideas that are probably still to be found in the company’s amplifiers today. How will the designer’s of today pass on their ideas in the touch screen age one wonders?
Imaging is good too, the soundstage reflecting the various recordings well with plenty of scale and energy, the Grateful Dead’s ‘Cumberland Blues’ being delivered in a less timely way than usual but with excellent flow. I also rather enjoyed an old Fleetwood Mac tune from Kiln House called ‘Station Man’, where Jeremy Spencer’s guitar playing is top notch and not unlike that of Paul Koss (Free). This band may not have hit the big time in 1970 but they were hot stuff and the Musical Fidelity lets you hear as much. Switching to a separate DAC and using one of the amplifier’s single ended line inputs produced a clear improvement in timing and solidity of stereo image. This combined with the power and sometimes startling ability to turn on a dime made for an even more enthralling experience. The sheer dynamic range on offer revealing that many amplifiers, even high power ones, are still reining in the potential of better recordings.
Timing and muscle
Switching to a fairly new pair of PMC twenty5.26i loudspeakers which have a lower sensitivity than the 802s but offer an easier load the sound initially seemed a little dry from a tonal perspective. After a few tunes this characteristic took a back seat to the spectacular combination of timing and muscle on offer from the M8xi, with track after track offering up oodles of detail in a very coherent and engaging manner. Even an orchestral Schubert piece was delivered with the tempo in full effect, this didn’t take precedence over the dynamics however which were delivered with gusto yet without any discomfort in crescendos. All that power really counts when you are trying to reproduce a ‘big band’ with real world loudspeakers, and it matters with smaller stuff too. Somewhat controversially I put on Nils Lofgren’s rather overplayed dem favourite ‘Keith Don’t Go’, just for old times sake you understand, and heard a fabulous acoustic guitar, a croaky voice and the energy of a live event in surprisingly convincing virtual reality.
Power does not equate too directly with quality unless it is clean, controlled and able to make a speaker do exactly what’s required when it’s required. The Musical Fidelity M8xi does that with knobs on, and rather nice knobs they are too.
- Type: Solid-state, 2-channel integrated amplifier with built-in DAC
- Analogue inputs: Four single-ended line-level inputs (via RCA jacks), two balanced inputs (via XLR connectors)
- Digital inputs: Four S/PDIF (two coaxial, two optical), one USB port
- Analogue outputs: One single-ended line-level fixed (via RCA jacks), one single-ended line-level variable (via RCA jacks), one balanced variable (via XLR connectors)
- Digital outputs: Two S/PDIF (one coaxial, one optical)
- Supported sample rates: up to 24-bit, 192kHz
- Input impedance: High-level: 25kOhms single ended, 50 kOhms balanced
- Output impedance (preamp): Not specified
- Headphone Loads: N/A
- Power Output: 550Wpc @ 8 Ohms
- Bandwidth: Not specified
- Distortion: THD+N < 0.004% typical, 20Hz to 20 kHz (XLR)
- Signal to Noise Ratio: > 86dB A-weighted (XLR)
- Dimensions (H×W×D): 185 × 485 × 510mm
- Weight: 46kg
- Price: £5,649
Manufacturer: Musical Fidelity
UK Distributor: Henley Audio Ltd
Tel: +44(0)1235 511 166