One mantra that Stuff never tires of repeating to anyone who'll listen is: “Upgrade your earphones!” Because whether you’ve got a music phone free on contract or spent a couple of hundred pounds on an iPod, a small additional outlay on a decent pair of buds will enhance your listening pleasure no end.

At £40 or less, Sennheiser’s CX400s fulfil our small outlay description. How about ‘decent’? Let’s find out…

Big audio dynamite

The CX400s pack considerably more punch than Sennheiser’s CX300s, which were our previous ear-bud point of reference. This is a serious hi-fi brand – the most expensive Sennheiser cans cost many hundreds of pounds – so we expected good audio quality, but these really were exceptional with a deep, rich bass that only very rarely overwhelms the mid-range. The top end is clear without being too sharp.

Like the CX300s, they sit very comfortably in your ear canal without getting overfamiliar with your eardrum, making them perfect for noisy commutes.

Not iPhone-friendly

The CX400s are around twice the price of the 300s, so what else are you getting for the money? They come with a new, shortish modular cable (and more robust splitter), so will work well with in-line remote controls and mobile phone adapters, and are perfect for armband-toting gym nuts.

As well as an extension cable, you get various sizes of rubber buds and a useful wallet-style case in the finger-shredding blister pack.

The only downside is that they're not compatible with the iPhone's recessed earphone jack without using an adapter. And, of course, splashing £300 on some Shures will provide an even more detailed listening experience. But despite this the CX400s remain our pick of the affordable headphone-upgrade pack.

Stuff says... 

Sennheiser CX400 review

These comfy, noise-isolating buds pack offer detailed performance for very little cash. Our new favourite headphone upgrades