I am pretty new to this hobby, but with a medical situation that keeps me here at home in isolation much of the time have been taking the time to clean up my system and enjoy my headphones much more than in the past. That way can spend me time listening in my music room without bothering others in the house.
I've been recording and using headphones since the '60's, but the level of performance in modern headphones is really remarkable. Back in the day, the Koss Pro-4AA were the cat's meow. However, now we live in a new era. The Koss phones are still excellent, but for me the DT-880 Pro's are my current "Flagship". I haven't heard the HD-600,650,800 but do have the HD-595 which I like for their forward presence and great soundstage. However, the clarity of the DT-880 is in a different league. The bass is markedly better too. Not louder, or more dominant, but the Beyer's can reach lower in a way that retains clarity and detail. For upper mids and treble, there's really no comparison as the DT-880 goes to places the HD-595 was not designed to achieve. Don't get me wrong here though, I love the HD-595's especially for vocals or source material where I want to have that amazing soundstage impact which is impressive.
I used Dr. Chesky's test files to hear the frequency response and you can hear the bump in the upper frequencies on the Beyer's. I most often run the DT-880's through a LIttle Dot MK III, but when I have a really good vinyl record or digital file, I still find my solid state amp (STR-V55) provides more clarity and detail over the tube amp. A caution here is that if the recording is not pristine or not recorded well the DT-880 will show you a lot of the flaws in a way that is distracting. The LDIII solves that, so I use more than one amp depending on what is up for listening. Some of the things written about the HD-800 and some Grado's sound familiar in this regard. I'm scared to try the HD-800 because the description of their sound is what I search for, but can't afford the big bucks and like my wife's redecorating, upgrading one thing leads to another, and another.
I'm working on a new recording project at this time and am using the DT-880's for monitoring and some mixing. Still listen to final mixes on a variety of headphones, monitor speakers, and different home stereos and car systems to make sure they sound decent on different systems. As all of you in our headphone hobby can appreciate, I find that "better" is a term I use less than "different" at some point.
My first audio equipment was a crystal radio and used my bedroom's window screen as the antennae, so I've definitely moved up in sound reproduction! However, I do want to point out that the crystal radio cost less than $2 brand new in 1963, and the current audiophile headphones and supporting equipment...................do not!
Happy Listening Out There Everyone!!
Mark
P.S. Here's my system at present. You can see I've cobbled together something from the past and something from currently available equipment. I've split it into two sides. One side is for digital files and computer listening, the other for analogue (vinyl, tuner, r2r, cassettes). Still interested in an upgrade here and there, but right now this setup sounds very good indeed!
DT-880 PRO, HD-424/595, AKG-240 Studio
TC-7510
LD MK III, STR-V55, SX-636
TC-651, TD-20A SE
SL-3350/AT4412XE/ATN12S
PS-T33/V15 Ty IV/SAS
TU-550 (Denon)
RCD-W500C
HK DC 520
Tascam 2488