I may be sick in some way:
Owned and sold many times more than this.
definitely a horder...
Pioneer SE-300 ans SE305 (just out of curiosity, costed nearly nothing, not used)
Koss KSC35 and 2 pairs of KSC75 (have gotten lots of usage in the past)
Jays V-Jays (somewhat similar to Koss thingies)
AKG K518 (modified, still not great)
Fostex T50RP both modified and EQ'ed (have not been used for years, great sound though)
Beyerdynamic DT990-600 (oldie, used it for many years, not used any more but can't part with it)
Beyerdynamic DT1350 EQ'ed and nubuck pads (used these on vacation now and then, need EQ, very dynamic and good SQ to me)
HD250-Lin II
HD238 (modified, wife uses it on vacation)
Philips Uptown 1x (modified, good SQ, not in use anymore)
Superlux: HD681 (modified), HD687 proto (modified), HD688 proto (modified), HD671 proto + production (modified), HD672 proto + production (modified)
Sennheiser HD58X proto + HD58X production (modified and filtered) occasionally used
Sennheiser HD650 (old, black driver) (EQ'ed) has been used extensively in the past. Now in the drawer. Not gonna sell it.
Beyerdynamic Custom One Pro (modified) did not like the stock version.
Sennheiser HD800 (EQ'ed).
NAD VISO HP50
Beyerdynamic DT1770 and DT1990
Favorites: HD800 (EQ'ed), HD688 Proto (modified), the production version is not nearly as good, DT1350 (EQ'ed), KSC35, HD650 (EQ'ed), COP (modified), HD58X (modified and filtered), DT1770, DT1990
Most usage: HD800 (EQ'ed)/DT1990, a prototype headphone I cannot name alas and DT1770 (closed)