I heard this pre-power combination at the 2014 Bristol Sound
and Vision Show in the Musical Fidelity Room, fed via a Musical Fidelity V90
DAC and playing through a pair of Spendor D7 loudspeakers. I thought the system
sounded pretty darn good, so I made a mental note to review the pre and power
amp – and the V90 DAC which was being used with them – after the show.
I soon found myself staggering across my home listening room
clutching the M8-500s. When I say staggering, I mean it! This stereo power amp
is a dual-mono power amp, with two entirely separate power amplifier circuits,
power supplies, and 670VA mains transformers, which electrically share only the
mains input. The transformers, power supplies, and heat-sinks (housing six
bipolar transistors per channel), contribute to its substantial 29kg weight.
This is a seriously heavy and bulky beast, but then it is rated at over 500W
per channel into eight ohms.
The M8-500s Power
Amp front view
It is a fully balanced design from input to output, with XLR
inputs, and bridged outputs (in which both + and – binding posts are ‘live’).
Unbalanced RCA sockets are provided for connecting unbalanced auxiliaries. The
well tried and tested power amplifier topography traces its lineage back to the
earlier KW and Titan models and is closely related to the more powerful M8500m
monoblock. I have not auditioned the M8500m or the limited edition Titan, but
admired the the KW 500, which was a very uncoloured and transparent amplifier
with vanishingly low distortion; this rose only marginally at high frequencies,
unlike many transistor amplifiers. It provided a smooth, uncoloured and
confident, yet detailed delivery, with enormous power reserves. If the M8500s
were to sound in the same ball park as the KW 500, I reasoned, this new design
has the potential for greatness.
The M8-500s Power
Amp rear view
The M8 PRE preamplifier, like the power amp, is also a
fully-balanced design from input to output, but unbalanced phono inputs are of
course provided for the inevitable unbalanced auxiliaries. Musical Fidelity say
this is a Class A design, but Class A operation is commonplace in preamps; it
is usually only power amplifiers where there is a need to use other classes of
amplification to achieve higher power levels and minimise heat dissipation.
Preamps only deal with small signal sat relatively low
power, and as the M8 PRE utilises tiny surface mount components tominimise
signal paths, one might expect the preamplifier to be much lighter than the power
amp. It is, but not by a lot. The M8 PRE weighs in at 17kg, which is no
lightweight, due to a hefty 350VA transformer (enough for a sizeable power amp)
and numerous regulated power supplies for different sections of the preamp. The
idea of multiple stabilised power supplies is to keep different circuits as
free from interaction as possible. So, combined with the very low claimed
distortion and noise, one might expect something special from this preamp.
The M8 PRE Preamp
front view
Unusually, these days, Musical Fidelity has provided a
built-in phono pre-amplifier with provision for both moving magnet and moving
coil cartridges. I am particularly pleased that Musical Fidelity has sensed the
zeitgeist and included a proper phono stage, maybe because I was the first
person to review Musical Fidelity’s first product, ‘The Preamp’ way back in
1982. It was a very fine, low-noise, transparent sounding preamp and it set
Musical Fidelity on the path to its current success. Unlike most modern standalone
high-end phono pre-amps, the input impedance is not user adjustable (it is set
to 47k Ohms, with no capacitance selection), so one cannot play about with
loading to fine tune the phono tonal balance for different MM and MC
cartridges. Also, 47k Ohms, while OK for high output moving coils, is not ideal
for those of low output, for which 100 Ohms would be more appropriate. It’s not
a disaster by any means (as we shall see), but some choice would have been
nice.
An unusual feature for a two-channel audiophile product is
the provision, via slider switches on the rear, to convert one pair of balanced
and one pair of unbalanced inputs to HT Inputs with unity gain. This is for use
with multichannel processors in home cinema (Home Theatre) systems. Also rare
these days is a genuine tape monitor switch.
