Upgrading from HD428s

Although I've seen it for much lower online, I wouldn't call $80 a ripoff price if you've used it for 3 years solid.

There's the Citiscape Uptown still for sale at $65 shipped at http://1saleaday.com/. About 5 hours left as of this post, I think that's a solid upgrade (and cheaper too).

You've got a whole lot of other options, though.

I have the HD428s, and agree that the cable is horrible. Out of the two pairs that I have, both of their cables got damaged at the exact same spot. One pair has been re-cabled, and the other ones is being re-cabled as well. 

Other than that, I can't think off the top of my head if  a closed headphone that has a similar sound signature as the HD428s exists. You might want to look for something different. Best to try some out at a music equipment store (Guitar Center if you're in the US), they usually have a lot of closed studio/DJ cans available to demo. If you want to stick with Sennheiser, the HD25-1ii are closed, really fantastic isolation, and sound amazing for rock,  very forward-sounding, nice tight , punchy bass (sometimes vocals can be a bit edgy though). They're also built like a tank, every part is replaceable, I've even seen them drop off some stairs without a scratch. Cable is average, but detachable. They are circumaural (on-ear), so if you wanted over-the-ear like the HD428, then sorry. They also might be over your budget, although I don't think you mentioned one. 

Best you read this as well: http://www.head-fi.org/t/433318/shootout-103-portable-headphones-reviewed-rock-it-sounds-r-shield-added-09-16-12

I had just meant that the sound, especially the upper-midrange to lower treble could be a bit aggressive, hence the term edgy. I would think that to be good for vocalists who might want a more forward presentation. I've never heard them, but I hear that the new Amperiors are a bit better (something to do with the shells, read this: http://www.innerfidelity.com/content/most-excellent-sennheiser-amperior-and-hd-25-1-ii). Another thing would be that there is a lack of soundstage size in general, especially compared to the HD428, which has a especially nice soundstage size for a closed headphone. Musicians might appreciate that though, as separation is really good. 

You say you enjoy proper vocals. Hard to find a closed pair that excels in that, but something like the Audio-Technica ES9W or the Vmoda M80 (I for one thought they had nice warm vocals) might do well.