These days it seems that there's nothing that the iPhone can't do, and thanks to accessory expert Griffin, it can now double up as a mini guitar amp, for all you axe-wielding Apple fans out there. So if you fancy yourself as the next Jimi Hendrix, Slash or er, the bloke from Green Day, then read on.

The GuitarConnect Cable works alongside the free iShred Live app from Frontier Design Group and can be used with an iPhone (4 or 3GS), iPod touch or iPad along with any electric guitar. But is it any good, and is it really a viable alternative to a proper guitar rig?

The first thing you need to do is download the free iShred app from iTunes and make sure that your iPhone, iPod touch or iPad is all synched up. Connecting the cable is a doddle - one end of the lead is plugged straight into your iPhone headphone socket, while the other end forks into two. One plug is for your guitar and the other is for plugging your headphones into and it shouldn't be too hard to work out which is which.

Probably the first thing you'll want to do once the app is fired up, is head straight for the guitar tuner. The display states which string it thinks you're trying to play and then the swinging needle graphic tells you whether the note is sharp or flat and lets you tune accordingly until the needle is in the centre. You can even set it to vary the tuning, for example by making it a step higher. Ideal for those awkward songs that require you to completely retune your axe.

To help you keep time when you're playing, there's also a metronome which be set at various speeds and which can click along in time like the real thing, or if you prefer you can turn the sound off and just use it as a visual aid. Obviously you can adjust the speed, and if you're using it with the sound on then you can vary the number of beats per measure.

When it comes to effects, you can pay to add on various upgrades, but the standard offering comprises an amp with an on button, a switch for changing between the clean and overdrive channels and a volume dial which, rock 'n' roll aficionados will be pleased to hear, goes up to 11. There's also a basic pedal board featuring Q-36 space modulator, HK-2000 digital delay (with tap tempo) and buzz kill. If that all sounds like complete nonsense to you, don't worry as there's a help option for each one to explain what the hell they are and how to get the best sound. 

There are six pre-existing preset effects including Crunchy Tone, Retro Vibey and Slap Delay and you have the option to create up to 48 presets of your own (the original six can be modified) which are divided into eight colour-coded banks. Tapping the coloured bar at the top jumps to the next bank of presets, or you can just swipe the screen to the left or right. It can take about 10 seconds for each preset to load, but it's worth the wait for the surprisingly impressive sound effects.

There's also an option that lets you pick out a song from your music library to play along to. You can even mark out a part of the song and loop it so that you practice a particular riff over and over again. This was really the only bit of the app where we ran into a problem. To avoid deafening yourself with your chosen tune, you have to turn the headphone volume down considerably and then you can't really hear what you're playing so while it's a nice idea, it's something that definitely needs addressing - perhaps in a future update?