warmest speaker cables you've heard?

@audioman58 @rushfan71 thanks for the heads up on the deulund. I was not aware of that brand until you posted. I have purchased from partsconnexion before, but mostly tubes and cardas cables.

@hshifi yes the puritan 156 is on my radar. I'm currently using AQ niagara1200. 

essentially, my system is pretty much setup just the way i want it. i have several headphones (utopia, susvara, abyss 1266) which all sound really good on the system. I would post my whole system here, but it is rather convoluted, and really, besides the point; I am only adding the Raal to the lineup just for variety and a different flavour, and as the Raal is already a confirmed buy, all that is left is to choose a speaker cable.

By what mechanism can a speaker cable boost or attenuate signals selectively within specific frequency bands?

I suppose that in a particular room, music might sound very subtly warmer or brighter when you introduce a slight change in gain solely due to a change in cable length or gauge. Even so, couldn't one manage those effects more effectively via DSP, tone controls, room treatments, speaker placement, etc.?

Don't know how DIY you are, but this might be of interest:  https://www.gr-research.com/cables.html

@tk21 the speaker cables are for a Raal speaker adaptor box. To SR1a headphones. These are extremely resolving headphones and from what I've read from other users, the headphones will reflect upstream cables and components.

If there is even the slightest chance some cables are going to give me a "warmer" sound, rather than accentuate/cause brightness or harshness, well it is a chance I'd be willing to take and spend on.

You want cables that are neutral. If you have overly bright speakers then maybe buy a warmer sounding speaker such as a British made speaker, wharfedale, tannoy, spendor, harbeth, etc..