Thanks to the plug-and-play nature of USB, it's not always necessary to open up your computer to fit new pieces of hardware. External DVD drives, hard disks and even TV tuners can be ready to roll within a few minutes of being attached.

Miglia has now pushed the boundaries even further by squeezing a sound card onto a small USB key. Once attached, Windows recognises and installs the device automatically, allowing you to listen to audio right away.

HarmonyExpress has a microphone input and a headphone output, but it will also support virtual 5.1 sound for surround sound speakers. Admittedly, because the device only has one stereo output, it can't push out a true 5.1 surround sound signal, but software built into the USB key is able to work its magic and create an artificial surround sound effect that will work with 5.1 speakers.

Audio quality is surprisingly good and, because the device uses fast USB 2, we experienced no jittering or audio-crunching, a common shortcoming of older USB sound cards. Even when using headphones we noticed a fuller, richer sound than with our PC's integrated sound card.

However, you may find that vocals echo slightly on music tracks. This is because the virtual surround sound effect is primarily designed for 5.1 movies and games and adjusts the stereo signal accordingly. A nice touch is the included extension cable in case your USB ports are blocked.

For £35,this is a bargain. We're not sure how many notebook owners use 5.1 speakers, but for a simple way to get sound on any computer, this is as uncomplicated as it gets.