Pre/Power Amplifiers

It wasn't a budget buy, but this late '70s integrated from the masters of the MOSFET spearheaded fresh thinking on amplifier design. But how does it sound today?

The advantages of using separate pre and power amplifiers over an integrated is a discussion that can still occupy audiophiles for hours. What was almost a necessity in the valve era became less technically significant once transistors were established, a quality solid-state preamp circuit being undemanding in terms of space and power.

Based on the popular Inspiration series, the new Revelation range offers upscaled performance for gimmick-averse audiophiles. Its new pre/power is a formidable package

High-end hi-fi offers many flavours of weird and wonderful design, technology and functionality. In a sense, that’s what it’s there for, in order to differentiate itself from more prosaic, modestly priced products. Yet it’s all too easy to get lost in ‘surprise and delight’ features, wild styling or wilfully alternative engineering – and lose the plot.

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.