It’s a cliché, but ‘the best just got better’! On opening the designer packaging you expect something new and brilliant and you will not be disappointed. The most noticeable additions on the iMainGo X are a rechargeable battery and a small external panel with an on/off switch and jack-plug access. This is a real advance on the iMainGo 2 which, until now, was unsurpassed in terms of highly-portable, battery-driven iPod, iPhone and MP3 player speaker systems.

Before going into any further detail, let’s just say that the sound from these stereo speakers (an incredible 4.2w in total) is truly amazing, it will astound you over and over again. The system gives a deeply full resonance, combining a highly tuned good bass quality without losing treble, which we all know can happen even on larger mains-driven systems. In fact, this excellent ‘balance’ of sound is another one of the advances in the iMainGo X which even supersedes its own previous versions. It fills our large studio with sound easily and goes beyond being the ideal portable compact speaker companion for your mobile device. The stereo output can at times sound a little tied tighter and undistinguished, but zooms past many other portable stereo speakers we've reviewed and is of course better than mono variants.

For those new to this iMainGo type speaker system, the compact unit is just 14.5cm x 9.6cm x 6.1cm and weighs 9oz. Every generation of iPod except the latest shuffle will fit into the case and of, course, it can be used with any device such as an iPhone, smartphone or MP3 player via the gold-tipped jack-plug, still with complete control over anything with a touch screen because of the clever see-through film on the back (this also makes a pretty good cover for the device inside, as the iMainGo is tough and rigid) or, with the new iMainGo X, you can actually plug your device in externally; a new and helpful feature. This means that when it is used with an iPhone for example, you can hold conference calls using the stereo speaker system whilst still utilising the microphone on the phone and just generally have more freedom of the device being used.

There are, in fact, four external jack-plug sockets. These include a dedicated headphone outlet that conserves the units’s power by working directly from the music player, a second headphone outlet which is also an auxiliary-out to play through other devices (including the possibility of ‘daisy-chaining’ through further iMainGo X’s to make a phenomenal amount of sound!), a microphone socket which can be used with electric guitars and karaoke machines, etc. and, of course, a charging port for the rechargeable battery pack. We have found the inclusion of a dedicated battery pack to be one of the really excellent features of the new ‘X’ version. Now you can just plug in and recharge the lithium-ion battery-pack with the charger cable supplied and there are no more sound problems caused by AA batteries that are losing power. There is a useful led light on the panel to let you know when the system is on or off and this also appears red when charging and green once the battery-pack is fully charged. The battery consistently lasted for a solid eight-ten hours from our testing and this was with usage of volume around 70% turned up. Falling a little short of the 12 hour claim.

The accessories included in the iMainGo X to secure a device are firstly everything needed to make sure that it is securely fastened into the system when zipping it in. This is much simpler with the ‘X’ than previous versions of the iMainGo. All you do is clip in a plastic cover and the device is held solidly in place with a foam backing; the time-consuming velcro straps previously used have gone. Accessories included within he box to protect the iMainGo X, are an extremely well-made carrying pouch, a wrist strap and an adjustable carry strap.

It is so good that iMainGo have not just sat on their laurels, knowing that so many of us already considered this device to be the one of the best portable speaker systems ever. Instead, they have gone to the trouble to make the iMainGo X have an even better design, with more usable features and, most importantly, truly impressive sound quality which is possibly the best we have come across in a portable system of its size, but it also challenges even larger, mains powered systems.