I hear a very subtle difference between the cables I've tried, and it's small enough that I'd have to say I'm unsure I'd be able to accurately pick it up in a DBT. So while I think cables can make a difference, the possible difference they make is so miniscule in relation to the difference between amps, etc that I agree it is, in audionewbi's terminology, the last thing we should worry about. The differences between good DACs can be subtle, and that between cables even more so. As a result, I'm not sure it makes a whole lot of sense to have $1k cables unless you have a serious system around it.
There are definitely other reasons to look at cables (even beyond the balanced aspect, which has a demonstrable benefit with some headphones), among which are aesthetics and ergonomics. My Q-Audio cable, for example, may not sound much different from other cables out there (I haven't tested, this is purely hypothetical), but the ergonomics are so much vastly better than anything else I have that I'll always keep it around.
With all that said... I still use a Whiplash silver cable with my LCD 2.1, as I believe I hear a very slightly more treble-tipped sound, which works well there. YMMV, of course.