I just got my Beyer T5p 2nd gens. today too. Running straight from an iPhone they can be cranked up louder than I can stand. Therefore, easy to drive. I'm listening to them as I write this out of my MacBook Pro using the Chord Mojo. No equalization.
I bought these used off eBay but I'm pretty sure they've never been used just by the packaging. They sound new, as in not burned in.
I have had in my mind what another user said about them on this forum recently: lifeless, a sound only Mr. Death would enjoy.
I took that to mean sterile and dark. These are closed cans so they're likely to be a bit darker than open cans, or so I figure anyway.
I've read comments about them leaking sound and having bad isolation. I'll address all these comments now.
I'm not sure what that other user was hearing to call them lifeless, but I'm going to assume he was being serious and not just screwing around. I've been trying to catch them being lifeless and only appropriate for Mr. Death. I have found a song or two that don't lend themselves well to these headphones. It was a Moody Blues song and something else that I don't recall but I suspect was recorded poorly. They sound kind of artificial playing that song. They love Stones songs. These aren't like "fun" cans such as Beats. These are kind of analytical. They're German after all, what else would one expect? I would put the sound on the cooler side instead of the warmer side. Kind of like Sennheisers can be sometimes. A cooler sound than my Grados. I think the person who said they were lifeless believes this to be true and for him/her it is. We all don't like the same things.
I have been comparing them to my Grado GS1000i, which isn't fair because those have hundreds of hours on them and are as smooth as they come. The GS1000i is one of the most resolving headphones I've ever heard and the T5p is very close to its level of detail retrieval. The GS1000i is more airy, has more depth but I expected that in this comparison. What I don't find in the comparison is any serious lacking in "mood" as I expected I might based on the prior comment. They do fall down somewhat on certain songs but then again, they probably only have the two hours on them that I've put there so far. They need more time.
I'll say this, in some ways the treble seems to extend further than my Grades. On the Diva Dance operatic song, the warbling octave changes way up into the high registers sounded super nice on the T5p. That song sounds superb on the GS1000i too but it was a hair better on the T5p. I'm still liking electronica better on the Grado though, overall.
My purpose in buying the T5p was to listen to music at Starbucks or the library so I need some isolation. Do they isolate perfectly? No. But you have to be listening at pretty loud levels for anyone to notice you. They let in outside sound but not a whole lot. Right now my wife and son are talking in the living room and I have these phones on and I cannot hear them until I take them off. When I put on the Grades I heard them while hearing the music, which is one of the reasons why I'm writing this with the T5ps on my head. I pushed the cushions snug to my head, turned the music up to the point where it began to get uncomfortable and she could hear it, but faintly, she said and she had to come close, like within four feet.
People who claim these "leak badly" possibly have trouble conveying scale in words. A little bit of faint sound escaping might be huge to some people but to others it barely registers. Some people listen to music way too loudly and sound is going to escape at certain decibels no matter what headphone you have. I think there is some leakage due to the pads being shallow, round and maybe not making a super-solid seal all around. You should have no trouble with these in an office, train, even a plane. Compared to my Grados, they hardly leak at all. The Grados let out tons of music and you hear everything outside.