Pre/Power Amplifiers

The Quad 22 control unit and II power amplifier have both enjoyed a presence on the hi-fi scene almost from its very beginnings. The 22 appeared in 1959 but the matching Quad II power amplifier had been around since 1953. Like most amplifiers then, the22/II was split into separate units, for mounting inside a larger cabinet. The compact 22 came with a basic metal shell so that none of its working parts was exposed should it be left free-standing.

Here’s a stylish new Meridian product right in the mainstream: a headphone amp/USB DAC with optional outboard PSU. It wouldn’t be a Meridian, though, without having some novel features. The cases are interlocking aluminium extrusions, double-skinned to enhance screening, and having no visible fasteners holding it together – clever. The PPS power supply is not dedicated to the PHA headphone amp but provides five 12V/500mA DC outputs on mini-DIN sockets, each incorporating dual-stage linear voltage regulation, for powering other Meridian products as well.

Schiit products benefit from a Scandinavian nomenclature – Asgard, Bifrost, et al – so, should this stunning little Magni headphone amplifier prove tempting, you needn’t approach the salesman with the embarrassing request, ‘Do you stock Schiit?’ As its company founders are seasoned designers of [quote], ‘fully balanced differential power amplifiers, fully discrete I/V conversion stages, audiophile D/A converters, relay-switched stepped attenuator volume controls in preamps, etc,’ they could have launched Schiit with whatever product genre they liked. Being savvy, they chose headphone amps. Schiit works with ‘simple, discrete circuit topologies’ for the analogue sections, while its DAC products feature ‘innovative bit-perfect management systems’. It also uses Class A amplifier designs ‘where practical – and single gain stages when possible’.

Ifyou’re old enough to remember Audio Research gear circa-1972, the new SP20 will tug at your heartstrings. This preamp’s fascia designer has revived the distinctive sectioned faceplates of the SP3 – the whiff of retro is much appreciated. Suffice it to say, gone are the days of a half-dozen toggle switches, mechanical push-buttons or old-school rotaries. The SP20’s buttons are limited to power on, mute and a choice of output to ‘speakers’ (power amp) or headphones, but not at once.

Krell’s new iBias range is claimed to be more efficient, or less power-hungry, than pure Class A. Paul Miller suggests that iBias is a modern take on the popular sliding bias circuits of the 1980s. So what is the motivation for it? Statements from the company suggest that Krell is doing its part to modernise the high-end, to increase its appeal to audiophiles who are not comfortable with bulky intrusions into their living spaces in a manner acceptable in the past. And yet nothing differentiates the Duo 300, physically, from hundreds of other ball-buster amps.

ModWright’s owner Dan Wright argues that ‘Valves are great voltage amplifiers and solid-state devices are great current amplifiers. ’ Hence the combination here: the top of the range ‘DM’ dual-mono version of the LS 36. 5 preamp, with its separate PS 36. 5 power supply, and the KWA 150 Signature Edition power amplifier.

Like the hardy perennials of audio horticulture, the standard valve amplifier circuits keep coming up fresh year after every year. And there’s been a new flowering in the family of beam tetrode tubes that started with the venerable KT66. This is the new Tung-Sol KT150, and the first manufacturer to feature it is Icon Audio, showing this tube off to good advantage in its MB90 MkIIm monoblock power amp. Built in Icon’s factory in China but finished and tested in Leicester, the MB90 MkIIm looks solid and handsomely-proportioned.