In 1990, Musical Fidelity made the first-ever Super
Integrated amplifier: the A1000. lt received a rapturous welcome and, even
today, second hand, is selling at high prices. The A1000 was the first of a
long line of Super Integrated Amplifiers from Musical Fidelity. Its children:
the NuVista M3, Tri Vista 300, kW500, M6/500i, NuVista 800 and NuVista 600 all
were equally enthusiastically welcomed to the audiophile world. The M8xi is the
latest and the best of the breed.
The M8xi is a separate preamp with two monobloc power amps
sharing a common chassis. Each has its own heat sink and separate transformer.
Genuinely dual mono. The preamp has its own separate power supply and is
mounted close to the input sockets. Consequently, PCB tracks are very short.
This elegant idea ensures that both channels' signals are ultra-low impedance
the instant they get into the amplifier. This is a significant detail. Each
channel has twelve big bipolar transistors - 200 amps peak to peak is easily
available. The metalwork is high quality. The front panel is a custom made fine
line extrusion of milspec aluminum. The custom made heat sinks have outstanding
dissipation characteristics and finish. The M8xi construction has a feeling of
solidity and quality.
Over the last 5 years our power amp circuitry has reached a
high state of development. In our never-ending quest for improving performance
and customer value we have been looking for ways to improve our designs. One of
the prime directives was to keep the low feedback configuration unchanged ..
continue with low feedback! The problem was how to improve efficiency and
performance without affecting the sound quality. If I say so myself, I think we
have come up with a brilliant solution. Our new M8xi power amp design gives
higher power, lower distortion, and better sound quality. Incredible but true.
The output stage efficiency has been increased thus yielding about 10% more
power for similar power supply voltage. More importantly, the whole driver
stage is pure Class A. We believe that this innovative approach has a
substantial effect on the sound quality. The sound stage appears wider whilst
the micro and macro dynamics have more impact. This effect is particularly
noticeable on well-recorded piano. I am sure you all know the piano is a
percussive instrument but in truth, this is rarely audible on most Hi-Fi
systems. Using an M8xi a piano‘s percussive nature becomes instantly obvious
and jumps out of the loudspeaker. lt is a surprising and satisfying improvement
to the sound quality. Vocals have more subtly, detail and presence. Large scale
music has depth, width, and incredibly dynamic presentation. All in all the
M8xi is a consummate all-rounder. Mostly it sounds like a small Class A
amplifier with huge power.
The M8xi also features a 5 input DAC. DACs are increasingly
common in integrated amplifier designs to add convenience when connecting a
variety of digital sources, so the decision was taken to build-in a DAC that
would perform to a high standard, independently of the amplifier. For added
integrity, the DAC features its own power supply. Based around the Texas
Instruments PCM5242 TI low-distortion and low-noise DAC chip, which is also
employed in many other premium products in the hi-fi industry as well as in
previous Musical Fidelity products, the M8xi has 2 x coaxial (S/PDIF), 2 x
optical (S/PDIF) and 1 x asynchronous USB Type-B inputs. The coaxial and the
USB inputs are capable of supporting hi-res audio streams up-to 24-bit /
192kHz, and the optical input is capable of supporting up-to 24-bit / 96kHz. For
maximal performance, all data streams are up-sampled and re-clocked by an
internal converter to reduce jitter and remove unwanted artifacts in the sound.
The M8xi delivers 550 + 550wpc into 8 ohms. It is extremely
stable and very linear. The distortion is low too; lower than 0.005% in the
audible frequency range of 20 Hz to 20 kHz. The M8xi has remarkable linearity
and consistency. lt is unconditionally stable and will drive any loudspeaker in
existence easily with ample power reserve.
Our Approach to Technical Measurements
In our view an amplifier should be completely neutral. lt is
‚a straight wire with gain‘. Easy to say but hard and complex to do. We want to
stress that we do not believe that the technical performance is an end in
itself. lt is a method of validating the total amplifier system concept. The
aim of our circuit/PCB designs is to have low feedback and achieve complete
neutrality, transparency, and great technical performance. The proof that we
are on the right track is the technical performance. We think that technical
performance cannot be summed up by the distortion at 1 kHz. Our view is that an
amplifier has to be able to satisfy a wide range of technical requirements
before it can be neutral.
Almost all loudspeakers have complex impedance and loading
curves. An amplifier must be able to maintain its voltage virtually, regardless
of loading. If an amplifier cannot maintain its voltage across the spectrum,
then the ultimate frequency response and distortion will be nonlinear. This is
The overwhelming majority of amplifier manufacturers only
talk about distortion at 1 kHz. We believe that this is only a fraction of the
story. From our perspective, an amplifier must have very low distortion from 20
Hz- 20 kHz and beyond. We believe that an amplifier‘s high-frequency
performance proves the total performance of the circuit and PCB layout. The
M8xi distortion hardly changes from 10 kHz to 50 kHz. An outstanding
achievement and validation of the circuit design and PCB layout.
Amplifiers should be quiet. If they are not, low-level
detail is irretrievably lost. Also, the dynamic range is seriously compromised.
Dynamic range is not just how much power an amplifier will produce, it is also
how quiet it can be. Dynamic range is the total from the quietest to the
loudest. The M8xi excels in this respect.
Precision Volume Control
The M8xi has a precision volume control. This ensures
perfect tracking right down to a very low level. This ensures perfect tracking
right down to very low levels which is unattainable with standard
potentiometers. This outstanding precision is achieved by laser-trimmed
The M8xi is effortless, fluid, and dynamic. lt doesn‘t sound
‚loud‘. lt just sounds right. The dynamics are handled with no drama or fuss.
They come and they go. There is no distortion; just pure undiluted music. lt
sounds like a superb small Class A amplifier but with limitless headroom.
M8xi - Specifications
Output (20Hz - 20kHz): 550 Watts per channel into 8 Ohms (870W into 4
Ohms); Peak 1.6kW into 2 Ohms
output voltage: 67 Volts RMS, 20Hz to 20 kHz; onset of clipping (190 Volts
<0.004% typical, 20Hz to 20 kHz (XLR)
ratio: > 86dB ‚A‘-weighted (XLR)
impedance: 25KΩ (RCA), 50KΩ (XLR)
response: +0, –1dB, 10Hz to 100 kHz
peak output current: 105 Amps
devices: 3+3 pairs (bridged arrangement) per channel