recommendation for speaker wire to soften the highs if possible


Hello,
I need help. My problem is my system sounds harsh on the highs to me. Not extremely bad, but enough that I need to fix it. My system consists of Ryan 610's, oppo Sonica Dac, and a Belles 150a hotrod amp. Speaker wires being used are old monster cable from the 90's. I also have monster cable rca. I mostly stream through Tidal. My question is can I make the desired effect by switching cables or should I add  a tube amp or pre amp. My budget on the wire would be around 300.00
Thanks in advance for any suggestions
128x128gunmetalzin
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.