One of the smaller differences between the SE425s and the SE420s lies in their comfort. The casings of the earpieces have been tweaked to better fit in the ear, so if you do want to wear them while lying in bed, or perhaps under a pair of earmuffs, you can do so without issue. On a purely aesthetic level, it's possible to get the SE45s with either silver or clear casings, and we can't help but be enticed by the transparent model - call us crazy but being able to see the inner components is just plain cool.
The downside of the secure over-the-ear fit is that the SE425s aren't the type of earphones you'll forget you're wearing. Not to say that the SE425s are uncomfortable - far from it. The SE425s are pretty much impossible to dislodge in normal use, so where you'll find yourself readjusting other earphones from time to time, the SE425s require no such attention. Moreover, Shure's foam eartips - already much praised on these site over the years - make getting an extremely snug and secure fit a breeze.
Notably, where the SE535s were considerably more expensive than the predeceasing model, the SE425s don't incur too high a premium over the SE420s. The latter can be had for around £185, making the £226 SE425s around a fifth more expensive, which is significant, but not prohibitive. The build quality of the SE425s is definitely better than the SE420s and if you plan on carting your earphones about in a pocket regularly that's an important consideration.
Those wanting to be a bit more protective of their investment - and we can hardly blame them - will welcome the inclusion of a hard carrying case with the SE425s. Additionally the earphones are accompanied by a 3.5mm to 6.25mm adaptor, an earwax removal tool and more tips than you could shake a stick at. There are three sizes each of silicone and hard foam tips, one set of soft foam tips and a pair of triple-flange tips.