Broken CX300ii earphones?

[melat0nin]

Hi all

A few weeks ago I bought a pair of Sennheiser CX300iis from Play for £15 (great price!). They sound great in general, but I'm convinced that the right 'phone is slightly weaker on bass. I thought I'd give it a while to see if maybe one of the phones needed a bit of burn in to match the other, but that doesn't seem to have worked. The right 'phone just doesn't sound right to me on 80% of sources I've listened to.

However I'm not sure it sounds sufficiently broken to be successful if I try to RMA it

Any ideas? Has anyone had any experience of this kind of thing?