However, there are at least two other important issues to consider. There’s no denying that the power amplifier does play a role in the sound, but because it’s near the end of the chain it doesn’t have the biggest impact on the total sound of the hi-fi. One should therefore perhaps question whether it really deserves as much attention as it usually receives.
More significantly maybe, do we really need an amplifier capable of such a massive power output? I can understand this being useful for a PA system required to fill a large space, and I guess some movie special effects (like explosions) might also make heavy power demands, but 2kW/4ohms does seem rather excessive for replaying music program with normal loudspeakers in a domestic setting. Perhaps personal prejudice is playing a part here, as experience has tended to make me suspicious of the most powerful conventional Class AB amplifiers, and I’ve long felt that the first Watt is by far the most important one.
Still, prejudice shouldn’t be allowed to get in the way. The fact that this is an immensely powerful amplifier certainly needn’t be a bad thing, nor that it operates in Class D. After all, the only thing that really matters is how well it sounds. But before going there, it’s time to curtail this opening rant and get on with a description of the device in question.
Although the plan dimensions are close to standard, given its power output, the M1 is an extraordinarily lightweight (9kg) and slim design (height is 5.7cms inc feet). That’s mainly because it doesn’t have the massive transformer and hefty capacitors associated with a conventional linear power supply, using instead a much smaller high frequency switch-mode supply. Anthem stresses that the ‘D’ in Class D has nothing to do with digital audio per se; rather it appears to use some proprietary variation on the PWM (pulse width modulation) theme. Each unit operates in balanced mode, using eight MOSFET power transistors, which not only run in a high efficiency ‘power factor correction’ mode, but also have a heat extracting pipe arrangement connected to the external side fins.
However, standing the amplifiers on a flat surface revealed that neither was itself quite flat (possibly because these demonstrator samples had done a lot of travelling). The optional rack-mounting ‘ears’ might be useful if a rack is available, but in fact we opted for specialist tripod supports for the listening tests (see later). The unit has rather more features than most of the type. Input connections are provided on both single-ended (RCA phono) and balanced XLR sockets, the latter with a 0/-6dB option, while the power amp may be activated in three ways – via a conventional front panel switch, a current sensor, or an AV-style trigger arrangement.