Speaker cables to smoothen things up

I love the sound of my system. Its dynamic and neutral and very lively. However, my taste to music have melowed somewhat, and im prefer a smooth, relaxing sound at the moment and was wondering if a speaker cable change would smooth things up somewhat and reduce the hardness and attack from my system ( not bright, just hard)
My speaker cables at the moment are some synergistic research tesla quad. I got this for free from my brother therefore ive not tested other speaker cables.
Interconnects are tchernov reference cables and my subwoofer inteconnects are fat oval ic.

The chain goes as follow
Mac mini with audirvana - nad m51 - densen b200 -densen b330 - neat ultimatum mf5 and genesis g928 sub.

Was wondering if a speaker cable change would smoothen things up. Its not to reduce the brightness of my system, my system is pretty neutral. Just want to reduce some of the attack and dynamic off the system. If possible, not wanting to change the amp and speakers.

Ive heard about van denhuls to do this, and ive got a good deal for a d352 hybrid cables. Also a good deal for a kimber 8tc ( the older black and blue version). Would these help? Any reccomendations is much appreciated

Just for info, my room is almost fully treated. Big drapes and rugs and diffusers and bass traps all over.