I am with Mr Bump. I switched to straight leads when they started becoming the norm.The curley ones I used were forever tangling up and the jacks were of poor quality ( at least those that I bought)/. I prefer to keep my tone intact and change it with eq as I see fit...but horses for courses.
The difference being that an EQ has (hopefully) a very linear rate of decay at a given frequency. The curly cord is much more complex in that the rate of decay is very nonlinear across the audible frequency band. It has 'holes' which change depending how the cord is laid out, stretched, etc
Yes, the cables are heavy, cheap, and prone to tangle/breakage. But they are also
musical in a way that an EQ cannot replicate.
I like using one curly lead somewhere in my cable run ... definitely changes the tone a bit. Whether it is an
improvement is up to the player.