I owned 8 headphones, and i modified with success all of them...
But my speakers/room beat them anyway... Why?
Because headphones ALSO own a "room"... The shell reflect absorb and diffuse sound like a room did...
Headphones also vibrates like the gear vibrate , suffer from too high electrical noise level floor like the gear and they had problem of their own with soundstaging, bass and dynamic... The ratio between crosstalk and crossfeed cannot be solved in the same way than speakers...But in the two cases it is a problem to solve...
It is the reason why after many years i give speakers another try...But this time i experimented with acoustic,vibration control and created my devices to lessen electrical noise...
Then headphones are very good solution because it is simpler solution ... But not a perfect solution for all....
But I might add that I also do a lot of listening on headphones, where those environmental factors do not come into consideration, and you can certainly tell quite easily whether it’s a ratty sounding source or not....