Warm sounding cables for STAX setup

I'm looking to get some warm sounding cables for my STAX headphone setup. Right now it is:

Bel Canto DAC2 -> STAX SRM-313 amp -> STAX SR-404 headphones.

I'm very happy with this setup, but it could use a little warmth. As it is now the setup is tipped up in the treble, and a bit too forward in the upper midrange/lower treble.

I'm on a strict budget (student) so I don't want to spend too much. And the cables will be bought used.

For RCA interconnects I'm looking at Kimber Hero. Also wouldn't mind trying a power cord, but no idea what to look for.

Thanks