recommendation for speaker wire to soften the highs if possible

. Richard Gray power conditioners are warm and will soften up the highs. Model 400 are below $300 on eBay.
. Vintage MIT MH-750 Plus speaker cables (white color) on eBay for around $300 are (very) polite, low white noise and really soften up the highs.
. Vintage Goertz speaker cables can drastically cut off (some) the highs completely.
*** Speaker cables will/may change characteristic of your system a lot so I’d suggest Richard Gray power conditioner. It mated very well with My Belles 150 Hotshot years ago. I then moved on up to Dave’s Reference a150 v2 and couldn’t be happier.

Richard Gray ruined the sound of my system.....quickly removed them.

I think he is winding us up. 

For the googlth time, systems in a room as individual as a fingerprint.

Blanket recommendations are not worth the bits to transmit them.

See http://ielogical.com/Audio/CableSnakeOil.php for examples of how the same cable reacts with just amplifier and loudspeaker XO order.

When one adds in low level interconnect, all electronic and room colorations buying a component on recommendation is odds worse than craps.

Strap a 4 ohm resistor and a 0.33uf cap wired in series across the speaker terminal/binding posts. 
That creates a very crude low pass that rolls off highs.  Let your ears be the judge.   Cost you $2 or so.  Better than buying $500 snake oil.