Posted by: Jane Douglas

The Sound Jacket is an iPod accessory by Radiopaq designed to enhance and amplify the sound put out by a fourth generation iPod nano.

With an iPod nano docked inside, the Sound Jacket acts as as add-on digital equalizer, dynamically processing the music to boost the bass and improve sound details smothered by MP3 compression.

There’s a headphone jack in the top and a standard dock connector in the bottom, along with a switch for toggling the sound processing on and off. On the reverse there are buttons to adjust the level of sound processing and the volume.

In fact, the Sound Jacket’s volume buttons wrest volume control fully away from the nano’s click wheel, putting the on-screen volume bar out of work. It’s a shame to trade off that visual feedback for a sound quality boost – but is it worth it?

There’s no arguing with the Sound Jacket’s amplifying abilities. With a pair of snug-fit earphones, the top volume level seems a few decibels short of rupturing your eardrums.

The top level of sound processing, however, is neither necessary or recommended, particularly for bass-heavy tracks. With maximum processing, that bass is boomy – even a touch distorted.

Moderate processing is more agreeable, though, plumping out the bass and picking out sound details. It does make vocal-focused tracks richer; flipping the processing on and off generally reveals the unprocessed MP3 to be a bit flat by comparison.

The obvious drawback is adding size to your svelte, naked nano. Weight is less of an issue; the pewter-coloured plastic Sound Jacket is surprisingly lightweight.

That’s partly because the device has no battery of its own, drawing power instead from the iPod (and cutting the expected battery life of the nano in half, down to 12 hours of audio playback).

In all, it’s a try-before-you-buy gadget; if you love the way the Jacket sounds, the size and battery issues can be overlooked. If not, save your £70 – maybe put it towards a really good set of headphones.