Buying advice

I have an Arcam FMJ A19 driving a pair of KEF LS50s. Maybe it’s a tad, just a smidge, bright. I don’t even want to use that word because I know it’s audiophile death. Maybe it’s better to say that I’d like to take a step—just a step—in the Harbeth direction. Import a rounder, smoother, warmer sound into the mix. And I’m thinking that speaker cables might help. 

I’m constrained by a very small bank account and grave limitations on room correction. 

There’s a pair of Morrow SP2 cables for sale on this site for $66. The price is right but are those going to take me where I want to go? If not, any suggestions? Please keep in mind the constraints noted above.

Crazy paranoia: The Morrows are 10 feet long as opposed to the 6 foot length of my current Q.E.D. cables. (From Q Accoustics.) That extra length can’t possibly affect the sound, can it?
Thank you.