[AdamTR]

  I would argue the DT880 and HD650 are the best headphones currently being produced by both companies. Contrary to popular belief here, you don't need to spend more money to get "better" sound.
 
Between the two, I'd probably choose HD650.

The DT150 and DT250 completely destroys DT880 for half the price unless you like a bright peaky sound!!

 

[moriez]

Well, from a technical standpoint, both flagships have problems compared to their predecessors. The HD800 exhibits a broad resonance at 6khz, and a corresponding peak at 6khz, that a lot of people don't like. The 600/650 are smoother throughout the frequency response. The T1 is even worse than the HD800 in regards to treble nastiness. It exhibits severe ringing 7khz and above, with very elevated treble response around 10khz. The DT880 in comparison still has a peak in 10k, but overall its treble is much more tame and controlled with less ringing.

So I can see a lot of people preferring the predecessors.

Thanks for the addition and insight.

 

[Thenewguy007]

  I would argue the DT880 and HD650 are the best headphones currently being produced by both companies. Contrary to popular belief here, you don't need to spend more money to get "better" sound.
 
Between the two, I'd probably choose HD650.

 
They are good, but don't compare to the T1 & HD800 when those two ar properly amped.
 
That said, if you won't drop $1500 on a amp to properly run them, then forget about it.
I had both the T1 & HD800 & used a ton of lo & mid-fi amps, they just can't get those headphones to sing unless you go over the $1,000 mark.

 

[sinesweep]

It took me nearly a year to decide but the first time I did some critical listenting to a T1, I knew it was the one. I'm a pro-audio/home-audio guy so there are certain things that I find very important. 
 
1-Spectral Balance
2-Tonal accuracy
3-Staging
4-Imaging
 
In that order and to me, the T1 was the best out of about 3 dozen I spent serious listening time on. I've listened to Studio monitors with TAD compression drivers & bass drivers, and these headphones came VERY close to my listening experience on those.