The amplifier uses a Class A circuit, but a 100W Class A design would be huge and impractical in Cambridge Audio's line-up, so instead the Edge amplifier uses a clever crossover displacement system, so that the amplifier performs as if in Class A even when running in Class AB. It masks the effects of Class AB crossover distortion by moving the point of that distortion away from zero-crossing point. This does effectively reduce amplifier distortion levels to extremely low levels across the board, giving an amplifier that effectively sounds like Class A but doesn't attempt to replicate an electric oven in the process. It still requires some fairly brutal heatsinks that you really don't want to carry badly. Still, it means the Cambridge Audio Edge A and I are blood brothers now.
That product design is a new level of minimalist. One button, one big volume knob, and a headphone socket. That's all you get. The knob has a concentric ring for source selection, but if you want balance controls or exotic readouts, the Edge isn't for you. Yet, despite this minimalist approach, the amp is surprisingly well kitted out. It features three analogue inputs, five digital inputs (including USB and Bluetooth) and a DAC that supports everything up to and including 32bit, 384kHz PCM and DSD256. A well-made handset reminiscent of Apple's TV remote on a larger, heavier scale, completes the package.
Overall, the industrial design is stunning, combining the sleek lines of amplifiers of old with an almost brutalist monolithic grey appeal. It looks good in pictures, but great in the flesh too. It doesn't try too hard, which is a bonus; products that light up like the bridge of the rebooted Enterprise are invariably impossible to navigate (AV amps are designed with 'granny settings,' suggesting that the amplifier needs a secondary control pathway for people not used to the amplifier. I prefer Cambridge's more basic approach.
The great thing about this industrial design is it makes a relatively complex action reduced to its core, and therefore simplifies it. No need for granny remotes or idiot-proof settings; the Edge A is the kind of amp you can learn how to operate in seconds, and yet it's highly specified. That all being said, I'd still like some degree of higher-level control on the main amplifier. Things like a balance control, for example. However, this feels like splitting hairs when the elegance of the product design is taken into account.
Elegant product design and minimalist control surfaces are immaterial if the amplifier circuits themselves doesn't live up to the task, and it's here things begin to go... very, very right. We've had something of an embarrassment of riches in terms of really good integrated amplifiers of late; Hegel, Primare, Devialet, and now Cambridge Audio all make products that don't just punch above their weight, they make you question whether you need to move into the that heavyweight class. Listening to the Edge A, I can't help but wonder if this is an AEGIS cruiser ousting the Dreadnoughts and Destroyers of old? After 10 minutes playing the Edge A, J.M.W. Turner's masterpiece The Fighting Temerairekept bouncing round my consciousness, and visions of rusting old amplifier hulks being towed to port to be scrapped spring to mind.
It's not necessarily that the Edge A massively outperforms those bigger, older amplifiers, it's just that it gets so close to what they can offer that it becomes hard to justify the additional expense and extra boxes required, when the Cambridge Audio Edge A gets you most of the way.
So, what is so good about the Edge A's performance? To quote the 'cheese shop' sketch from Monty Python, "Well, it's so clean!" Not only is the Edge A uncontaminated by cheese, it happens to be one of the most quiet, clean sounding, honest, accurate, detailed, dynamic, fast, coherent, open sounding amplifiers around. It gives great soundstage too. It doesn't warm or rose-tint the sound, but neither does it eviscerate the music in the process.
How that equates in musical terms is simple. Pick a piece of music, listen to it. Try and stop listening to it after the first 30 seconds. Then repeat until musically satisfied. Musical examples are almost pointless here; you play ZZ Top, you get ZZ Top, you play Abba, you get Abba. You don't lose anything in translation and you soon stop talking about sins of omission and commission, because it doesn't play those games.
Bluetooth is an interesting aside here. Normally an afterthought, Cambridge claims to have nailed it. I'm not quite so convinced; wired digital inputs are better, but the gap is closer here. Even the headphone socket has been well considered, although it doesn't really figure as a strong suit in the amp design. I'd give it a 'good plus'.
Musical examples are always considered a sign of having done the job, as if having a review without one somehow invalidates the whole review process. The first track I put on kind of summed up the whole Edge A. Out came Mahler's Eighth Symphony [Solti, Decca]. I played the opening bars with suitable gusto, and what came out of the loudspeakers was rich, full, powerful, and as if the loudspeakers had just grown in stature. Then I moved to Kat Edmonson's 2010 earworm 'Lucky' [Way Down Low, Spinarette], and the speakers shrank back to give it an appropriate sense of scale. The clarity, definition, and articulation of the Edge A was ultimately a problem of my own making here, because I'm still trying to get that damn song out of my head weeks later!
The Edge A doesn't have it all its own way. There are still big loudspeakers that need big amplifiers to drive them, and some systems in need of added brightness will not find it in the Edge A. I can't imagine an amplifier like this will be able to cope with sub-ohm minimum impedance loads seen in some larger loudspeakers, but in the real world (or at least the real world that buys £4,500 amplifiers), the Edge A will be partnered with more sympathetic loudspeaker designs without crazy amp-crushing phase angle problems. In such cases, I genuinely think this is all you need. Job done! Game over.
In a way, I’d like to see elements of the Edge NQ preamplifier filter to the Edge A integrated amplifier. Specifically, the built-in Chromecast and UPnP network playing (which includes internet radio). Of course, that implies a future Edge product that adds those elements without being a preamp in its own right (or implies the use of the Edge NQ preamplifier and Edge W power amplifier in place of the Edge A, which brings more to the table, but adds an extra box and £1,500 to the price tag in the process). Regardless, these would be worthwhile additions inside the Edge A instead of using up one or more of its deliberately finite number of analogue inputs.