Supra Cat 8 Ethernet cable

@ram18 ok. If the router/switch has a ground screw, try grounding it. It may or may not be an audible improvement but definitely worth a shot and will cost you far less than buying and trying more cables. Free advice, take it for what it’s worth. 

The Supra Cat8 cable saw various components come and go in my system but it was never a culprit of any problem. It was a notable upgrade in sound vs the standard yellow Ethernet cable.
IMO, you have 2 suspects when it comes to isolating the source of potential harshness in sound…your XTZ amplifier, which is a budget Class D amp, and your Klipsch speakers. Some Class D amps with an exception of a few in the thousands of $ price category (i.e Bel Canto Class D ref monos) can be a bit hot sounding in the treble although I admit I never heard XTZ, it is just a suspicion. Couple that with Klipsch and you may end up with the sound you’re describing. It’s possible that adding the Supra Cat8 had simply exposed some weak links in the chain.

Like I said earlier, don’t get hung up on cables at this level. Especially Ethernet.

If you like your klipsch speakers and want to keep them, a good solid state Class A/B or even a tube amp may be your ticket. There are many choices out there especially on a used market that will not break the bank. Anyway…just my thoughts. 

@audphile1 Thank you for your detailed explanation. Yes  Class D amps are traditionally  hot sounding. The XTZ however leans to a neutral delivery. Honestly its a great steal for the price. As for my Klipschs  refrence premiere speakers they are a tad bit bright not as bright as the ones of the past that Klipschs are known for. I have a tube Schiit Freya + preamp which tones down the brightness and helps give a smoother feel.  So far with my stock 5e ethernet cable, the combo somehow  sounds warmer. 

But you are right, maybe the Supras are revealing  the true effects of the system compared to my stock ethernet cable. Sorry for a noob question. How does one ground a router. Mine does not come with screws and it is just placed on my console. 

There usually is a ground screw on the Ethernet switch. What model is it? Or are you referring to a router as a switch?

Also, I forgot to mention room acoustics. Probably most important and most neglected as we tend to focus on easy changes such as cables. This should definitely be at the top of the list. 

@audphile1  Yes  sorry I was referring to my router.  I have 3 big absorption panels on the wall opp my system. Initially, I had a carpet on the floor but the sound became too deadened. So  I removed it. The sound becomes more alive without the carpet.