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i-Steroid iPod valve amplifer: Drugged up, or quick and nimble?

An iPod valve amplifier? Didn't we stop using valves in the '50s? What can this little box offer the modern music fan?

The warm glow of valves was once a familiar sight inside electronic equipment. These tiny fires of electrical power, burning so bright, give ancient tech a romantic appeal, something that today's innocuous silicon diodes lack.

For the uninitiated, valves look like small lightbulbs and are generally used to amplify a weak input. Stand by for some science...

Valves rely on the fact that a powerful current jumping between two metal elements in close proximity within a vacuum (the bulb) is easily suggestible while travelling in the gap between the two elements. By inserting a thin gauze in the gap between the elements and sending a weaker current through it (for example, the input from an electric guitar pickup), the stronger signal will pick up the characteristics of the weaker one. This is the basic principle behind valve amplification. Valves were superseded by silicon in most electronic equipment, but we still use them in specialist audio equipment today because of the subjective sense of warmth and tone they produce. Lesson over.

The i-Steroid uses a single valve to tonally colour the music from your iPod. Purists will have several problems with the i-Steroid's approach. First off, the valve is part of the unit's sub-woofer component. Valves are highly sensitive to vibrations, so it seems odd that they've put the valve stage in the most vibration-prone part of the unit. Secondly, valves vary wildly in quality and simply using a generic valve will offer little benefit.

These theoretical reservations aside, the i-Steroid sounded fairly capable in our brief listen this morning. We'll be putting it through a more intensive workout over the next few days to discover whether it makes the grade. The i-Steroid is available in the UK now for £129, which is a very competitive price if it does offers good performance. Expect a full review soon. -CS