just bought a pair - will post reviews when I get them!

  The DT880 is more "true to life", but the sound of the DT990 is slightly more clear and open, as well as much more "exciting".   The T1 is all these things to an even higher degree (detailed, spacious, exciting because of the detail and accuracy) , but it's way more expensive.

  Do you listen to mostly electronically generated (anything that uses synthetic sounds) or recordings of live music?

I've owned the srh440 and I think they were great.

Bumping, wanting to make a decision in the next day or so

For the headphones you're using you should be worrying more about how easy it will be to solder, rather than the quality of the wire. This is because the headphones' internal wiring is the same cheap-medium quality that the original cable was made of, so a high tier cable won't help.

I'm looking for an upgrade from the DT990 premium, I mostly play games and watch anime/movies on my computer and have a Musiland monitor 03 US DAC and a Fiio E09k amp. I've been looking at the T70, and to a lesser extent at the DT880, since I owned the T1 at one point and loved it (!) but had to...

You could maybe get $10-$20 for the broken headphones on ebay, put that towards some new ones. The materials alone (solder, solder iron) will cost you quite a bit, and then you've got your time, and the high % chance of failure for a novice using a soldering gun on fine wires (I know I wouldn't...

any sort of audio wire should work, I think. Not sure if it has to be the same thickness.

Quote: I stand corrected, it seems. Beats must have expanded its lineup since I last checked.

T70 not smooth enough for you? The only closed cans higher tier than the T70 are in another price bracket altogether, I think. 

The momentum, from what I've heard, has some top notch build quality, with a bassy but still respectable sound.

Well, if it's any comparison, the T1 is often compared to the HD880, and I find the DT990 (250 or 600 ohm, really not much of a difference) to be 90% as good as the T1, and I've owned both.

Let me first start by saying, since you appear new:   Not trying to be mean, but beats have a sort of reputation here as an overpriced headphone with a sound quality warranting 1/4 the price that it is, and although the build quality is actually pretty nice, it distorts the sound to...

Price on the T70 is $280, price on the 880 is $200. I'm using a fiio E09K desktop amp with a musiland monitor 03 US DAC.