Gadget: Auzen i.Fuzen HP-1 Headphone Amp & Backup Battery for iPhone 4

It’s a great multimedia device, but it’s not a particularly good phone. It drops calls; it doesn’t have great sound quality, and that lovely big 3.5in retina screen sucks dry battery life quicker than a vampire orgy.

Realising these chinks in the iPhone’s armour, Auzentech, a tech start-up company based in California’s Silicon Valley, have created a combined headphone amplifier, back-up battery and hard shell in one. I’ve tested a few supposedly slimline iPhone cases that double as battery extenders and the vast majority turn the sleek lines of the iPhone into those of a sumo wrestler. The i.Fuzen only adds about 1.5cm to the height of the iPhone and a few millimetres to the depth. It took about five hours to charge the case initially via USB, and this will effectively double the iPhone 4 (or 4S) battery life. I got at least another five to six hours of extra talk time in my tests.

The most unique feature is the built-in headphone amplifier. The bottom of the case has two sockets for either low-impedance (the majority of in-ear earphones) or high-impedance earphones (normally expensive studio-style headphones). A press of a separate button enables the amp. I quickly switched between the iPhone’s normal earphone socket and the i.Fuzen’s - the difference was a sound turbo charge that nearly turned Britney Spears into Bonnie Tyler, with audibly more precise treble, punchier bass and a wider soundstage. Expected to retail for around £89 in the UK, the i.Fuzen is the equivalent of heated leather seats, or flying first class - hardly essential, but a lovely treat.

Auzen i.Fuzen HP-1 Headphone Amp & Backup Battery for iPhone 4

Due to launch next month at £89 from www.amazon.co.uk, www.play.com and www.amp3.co.uk, see www.auzentech.com for more details