Quick and dirty: T5p doesn't have as much bass presence nor punch as these (DT1770). But what the T5p lacks in bass, has in mids and a less "hollow-ish" sound which I've been hearing on the 1770s. T5p's sounds more boosted up top but it's probably due to lack of bass being present. Overall in comparison, 1770s are warmer.
SRH1540 was almost basshead cans to me!. Good mids and very good imaging but a bit too much mid-bass. Right now I don't find the 1770 as bassy or warm as the 1540s. Something that surprised me on the 1540s is they they almost had the "V-Moda" approach to "tame" the treble (from 4khz or so). Maybe not as exaggerated, but to my ears the 1540s lacked "life", lacked air. The DT1770 although capable in the bass department, it is definitely NOT as "muted" up-top as the 1540s. So I guess it would be a "preference" thing. Both come with lots of accessories, extra pads, and both are comfortable, etc. The 1540s can be found at a way lower price though... both are enjoyable. One thing that made me sell my 1540s was...
leakage!!!!! The 1540s leaked quite a lot at decent volume levels. My test is always at work since it's a cubicle environment. If someone can listen to my tracks, that headphone failed...
And I'm sorry to say that... at least with the velour pads on, the DT1770s seem to be suffering the same fate!
I was just asked if I was listening to "Merengue" (tropical Latin America music) by a co-worker!!!
(and yes I was... she could hear the trumpets and sax playing!).
It might be due what I guess are the bass ports.
Thing is that these call for a bit of volume, and when applied, leak! Oh well... will keep on testing.
Right now: Sony NWZ A17 (no audio settings enabled -- no clear bass, no eq, no nothing) --> Schitt Magni