Integrated Amplifiers

In some ways the AX-5 represents a distillation of Ayre’s ‘purist’ philosophies, as it employs both the company’s ‘Diamond output circuit’ and the elaborately-designed volume control trickled down from its flagship KX-R Twenty preamplifier. In the fully-balanced zero loop feedback AX-5 integrated, Ayre eliminated the preamp stage altogether and simply made the gain of the power amplifier directly adjustable using VGT (Variable Gain Transimpedance). The volume knob on the right of the fascia acts as an encoder to control a pair of motor-driven Shallco silver-contact rotary switches (one for each channel, conjoined using toothed belts), each of which contains dozens of hand-selected, low-noise resistors. Volume level can be adjusted over a range of 69dB in 46 steps of 1.

With the Danish company in the doldrums come the early '70s could this reimagined receiver with phase-locked loop decoder deliver on its promise of 'high fidelity' sound?

Bang & Olufsen's first move into the world of serious hi-fi came in 1967 with the introduction of the Beolab 5000 amplifier and Beomaster 5000 tuner [HFN Dec '12]. These defined the European state of the art at the time and were as successful as their high prices allowed. The company then distilled these two units into the Beomaster 3000, which offered similar qualities at a more accessible price. It lacked the sheer power and versatility of the Beolab 5000 but sold strongly throughout a long production run.

With its four-channel amp and on-board SQ decoder, this '70s receiver was the lynchpin in what was arguably the most leading-edge quadraphonic system of its time...

The era of quadraphonic sound was not the hi-fi industry's finest. Appearing around 1973 but moribund by 1978, quadraphonic was the first big marketing failure by a sector that had so far enjoyed unalloyed success in convincing the public to buy into its latest developments. Confusing advertising, a damaging format war and a lack of consumer demand all played their part in the downfall of a concept which, at its peak, had been hailed as the future.

Guided by theory and practice from the costly REX-series, traditional output pentodes are usurped by a pair of power triodes in BAT's fully-balanced tube integrated amplifier

There's a certain amount of extra-curricular activity that can come with using a valve amp. As with their fellow stalwarts of hi-fi – turntables – valve amps present opportunities for setup, tweaking, and maintenance, and for some that's part of the appeal. Balanced Audio Technology's new £9995 VK-80i integrated, however, is intended to be 'plug-and-play', and provide a user experience more in line with its own solid-state models than some hot bottle contemporaries. All the thrills of the tube sound without the fuss? Where do I sign?

Boulder by name and industrial design, the 866 integrated is no mere rolling stone. With optional streaming and huge power under the bonnet, it's an unstoppable force

The Boulder story begins in 1984, with the release of the 500 Power Amplifier. A professional audio company back then, Boulder's stereo model was destined for music studios and broadcast suites, but founder Jeff Nelson soon realised the hardware had domestic potential too, resulting in the 500AE 'audiophile edition'. Today, nearly 40 years and an expanded product portfolio later, the Colorado-based manufacturer remains a darling of the high-end hi-fi scene, albeit one whose designs still have a 'pro audio' air about them.

Hailing from down under, Burson’s flagship Voyager series is ruled by the Conductor DAC/preamp/headphone amp – rated at a stupendous 10W, and with features galore

Though perhaps not so well-known in some hi-fi circles, Australian brand Burson Audio has built itself quite a following among head-fi’ers – those devotees of headphone listening – thanks to an impressive range of amplifiers dedicated to that cause. Its models range from the £849 Playmate 3 up to the Conductor Voyager we have here, at £3900 in standard guise.

Named after Cambridge Audio’s founding father, this new integrated amplifier includes a DSD-compatible DAC and Bluetooth aptX HD. But does it really have an Edge...?

There’s one very noticeable thing about the new Edge range from Cambridge Audio – well, apart from the fact that these hefty new high-end components are quite a long way from the company’s usual entry/midrange territory, that is. Look at any of the new products and you’ll notice the branding – it simply says ‘Cambridge’, as if to set this range apart, and fit in with the minimalist-but-purposeful vibe of the whole lineup.