I've been thinking about this and I think the problem is not the cables but within the signal.
The final sound of the loudspeakers depends in 90% on the amplifier signal, and in 10% on the package of information we try to preserve with cables.
The cables cannot add anything from themselves, as being a passive element, they have no means of getting any kind of extra information.
At most they can keep some details for themselves, filter out some nuances, accent others, but we are always within the amount of electric impulses provided by the amplifier.
Keeping things short it is about the idea, that a certain cable should keep as little to itself as possible, “disappearing” from the sound path, providing the highest possible conformity of what comes in on one end with what exits on the other end.
So essentially, you are trying to find cables that will chop off or round off the highs.
My experience with Digital and within my system was that working on power and mechanical vibrations was beneficial and totally removed any harshness and fatigue.
If I can give you some recommendations pls try the following (since you are only streaming).
-Maybe start with a LP player or CD player and see if the problem disappears? Like this you can maybe validate the fact that it comes from the streaming chain.
-Start at the beginning ie your orange box. Try to replace the LPSU by a better one, try solid copper core DC cables between the LPSU and the box, and place both on isoacoustics graphite. Then pls turn off the wifi of the orange box and use a separate wifi router. It's really harsh with the wifi on.
If it doesn't help, then work down the chain. You'd be very surprised what a small thing such as a DC cable can make as a difference.
-If you have the possibility, try to consider dedicated power lines vs power conditioners. I haven't tried the Audioquest but I tried others and for me I thought that they were introducing a bit too much energy making the sound a bot too forward to my taste. The sound via the dedicated lines is more balanced and natural. Try this cable:
oyaide-ee-f-s26-v2-cable-secteur-cuivre-102-ssc-fep-blinde-3x33mm-o-14mm
www.audiophonics.fr
-Try isoacoustics orea pods below the power supplies and your streamer. It also helped reducing fatiguing highs and it will open up the top and the soundstage too.
-Maybe try cable lifters too. Maybe these cables don't like being on the floor. An interesting read:
Bunking Cable Lifters: Roger Skoff Writes About the Other Side of the Discussion
positive-feedback.com
My experience is that power quality throughout the chain and vibration control was the most effective treatment for harshness.
Pls consider giving it a try before you replace your nice cables.