[Eagle_Driver]

For me, that would be the Sony MDR-V6 and its "professional" lookalike MDR-7506. That was my entry into "good" headphones, and still holds up quite well with my more recent purchases of full-sized headphones (most of which I subsequently sold off). The pair of the 7506 that is curently in my possession is my third pair.

Second was purchasing Sony MDR-V900 and its "professional" sibling MDR-7509 (both pre-HD versions) twice (combined). The 7509 is currently in my possession but doesn't get used much (if at all).

I forgot to specify my reasons for the sale and (re-)purchase:

It was because I was going through "upgrade-itis" at that time, and sold those to fund my higher-end headphone purchases. But after I sold off most of my home audio stuff or left them behind at my old place in the move to a newer-to-me place that had absolutely no room at all whatsoever to accommodate full-sized audio equipment, I downgraded my headphone collection to just a few. My 7509 was one of the very few headphones that made the trip to my newer place (since I had sold off practically all of my better headphones and all of my headphone amps when I had financial problems back in 2008-2009), and I have since purchased a pair of the 7506 (for the third time) and a pair of the Audio-Technica ATH-M50x, as well as another cheap pair of the JBL in-ear phones and a pair of the JVC Gumy wireless (the isolating version). The last two are good values, though I still feel that there may be better in-ear headphones (from lesser-known or even unknown brands that aren't sold in stores at all, but could only be obtained through online orders) for the prices that I paid for them.

And since my only audio sources are now my smartphone and a computer, I now don't feel any need whatsoever to upgrade from what I currently have. And I am currently on medical leave from work, so I cannot afford anything significant anytime soon.

 

[msuroo]

A lot of Sennheiser love in this thread, ha. I’ve never bought the exact same pair twice, but my first pair of HD580s back in like 1999 set me on the path, and have been through a couple variations since.

 

[msuroo]

For me, that would be the Sony MDR-V6 and its "professional" lookalike MDR-7506. That was my entry into "good" headphones...

Wait, crap - how could I forget about these. my MDR-7506s predated my HD580s by a couple years, and I definitely bought a second pair at some point.

 

[Slim1970]

Beyerdynamic T1's (3 times)...settled on the T1.2 LE (Black Version)
HD650 (Twice)...Better the second time around now that I'm driving them balanced out of a speaker amp
Klipsch HP-3 (Twice).... These are keepers this time
Beyerdynamic DT1990 (Twice)...The best headphone I have for heavy metal and rock
Oppo PM3 (Twice)...Best portable can I've owned, that midrange..
B&W P9 (Twice)... Great sounding headphone but I didn't like the fit

 

[SonyFan121]

I have sold a few over the years, but the model I've sold and eventually keep buying again, is the K702. I've owned 3 in total now. At this stage I have realised that no other open-back headphone will ever please me as much as the K702. It's just the way it sounds, so natural in my opinion. 10 years ago it was state of the art, costing around $500 USD, now it's been superseded by plenty of other open-back models of different manufacturers, and it can now be had for less than $150 USD. But I don't care, no other open-back headphone can compare to the naturalness of the K702, in my opinion - Especially the Austrian version.

 

[Tsukuyomi]

I sold my Th900mk2 due to comfort... but its been a while since i last wore them or maybe something was off with my old pairs fitment for the headband or pads.
I'm tempted to re-buy it... but 1899$+tax is a steep re-purchase... not sure i can handle that
I'm also tempted to buy another pair of B&O H6(2nd gen) because i like them so much as portable/outdoor cans. and B&O discontinued them so gotta stock up! but we'll see... if B&O make a new spiritual succesor to the H6's i may buy thoes instead of another H6 Pair.

 

[chimney189]

I sold my Th900mk2 due to comfort... but its been a while since i last wore them or maybe something was off with my old pairs fitment for the headband or pads.
I'm tempted to re-buy it... but 1899$+tax is a steep re-purchase... not sure i can handle that
I'm also tempted to buy another pair of B&O H6(2nd gen) because i like them so much as portable/outdoor cans. and B&O discontinued them so gotta stock up! but we'll see... if B&O make a new spiritual succesor to the H6's i may buy thoes instead of another H6 Pair.

I'm very tempted to buy another TH-900. I agree that the comfort was so-so. It felt pretty loose on the head, but the sound was incredible -- except the strident treble at times.

 

[Redcarmoose]

I’ve never sold a headphone, but I did sell a guitar one time that I miss dearly. Lol.