recommendation for speaker wire to soften the highs if possible

@johnsonwu do you know specific size and voltage for the cap (and resistor)?

I just corrected nasty, harsh tweeter highs/fatigue. 
A friend brought over some Dueland wires and they did the trick. 
Myself and a group of serious audiophiles tried all the things suggested in this thread. 
I was to the point of breaking out the ice picks and sticking them in my ears...
Just  saying, you might seriously consider the Grannying option. It shouldn’t be too expensive and you may not need anything more. ( I don’t know Grannying, I’ve never had contact with that person). 
I’m with you. Most likely the Monster cables are the problem. 
Good luck. Keep us posted. 

Ok. So I just looked up on Duelund wire 12awg from PartConnexion.com and it’s $19.95/meter for a single wire which translates $159.60 for a pair of speakers in 2 meter long?
Isn’t that too much for a bare wire without shielding?

I’m telling you, contact Grannyring. 

Hi, I made my own cables simple easy alittle time. Ordered from Blue jean wires, 25ft 12 awg, OFC Copper gives sound a softer note IMO to my ears. Silver is higher pitch, harsher to the ear, brighter. Imo to my ears. Your equiptment SS or tubes, i hear tubes soften the sound, type of speakers, room materials. Rug v wood floors. 
I have Yamaha RV A 3050. Maybe soon i will get a tube amp, but for now it sound just right for me. Hope this helps.