Should I buy the HD6XX though redundant

[monsterdonkey]

I have a set of HD600 phones that are about nine years old. So far so good, but recently I noticed a crackle in one driver when a particularly low bass note occurred. Once I blew a driver in a Grado SR60 and this sounded like it could be the same thing. They’re mostly good except for that one time I heard a crunchy noise. I’ve read the HD6XX is not that different from the HD600 so it seems silly to have both, but then I’m also worried that eventually the Drop deal will disappear and I’ll be stuck with a dying set and few cheap options. My budget is pretty low.
TLDR: buy now and store for when I need them? Or upgrade today! Or just wait, maybe the HD600s are just fine and I found their limit that one time.
Speedball Crack

[Paul Birkeland]

I would pop the driver out and see if there is a hair or some other object stuck in there that's making the noise.  If need be, you can replace the drivers.