Ethernet and USB cables

Do premium Ethernet and USB make a sonic difference? I have very good speaker and DAC to amp cables but, all the others are just inexpensive generic cables. I’m running Innuos Zenith MK III and about to try out a Phoenix USB. Just looking to get the most out of the system w/o throwing away more $ (unless it works!).
I have used high quality USB cables including a WireWorld Starlight Platinum 7 and Audience FrontRow.  Each brought substantial improvement to my digital setup at the time.  Last week I purchased  a Sablon USB 2020 cable to go between my Wolf Audio server and my Gryphon DAC module and it has far outperformed the ones I previously enjoyed.  
I systematically evaluated USB cables for my ~$7K former headphone system and ultimately settled on some $500 USB. This was cost effective use of the funds for what I could hear. 

My dealer / friend that I trust completely said the biggest difference he has ever heard in an interconnect was an Ethernet cable.

So yes… I would imagine 5% would be a starting place, then try a couple less and more.
I just went from a cat 5 cable to a cat 6 to a cat 8 over a two week period, 15% faster speeds on average both directions and STOPPED a slight buffering issue I was having when traffic was high.. OR the SUN was having a fit.. :-)

It would produce sibilance, it drove me NUTS..

Then I really listen after 3 weeks of breaking in and settling..
A 14.00 cable, I kid you not.. 14.00 dollar cat 8 from Amazon, it's a ribbon (flat), vs my 220.00 dollar Cat 6 humpty dumpty cable.. Teflon this and silver that... 14.00 dollar cable from Amazon tore it UP. Hocus Pocus, Bofus? It was magic. The 1 and 0s are in perfect order...

I'm gonna do the whole house in Cat 8, ribbon. I'm impressed.

I got a brand new laptop just for the new setup we'll see. 17.3 flip back with a hot rod sound card, faster CPUs and Dual SSDs RAID for speed ONLY.. Music ONLY, Speed Only, speed only, speed,     only.  puff! :-)
Machines on drugs.. LOL

Now for a new DAC

I'm DONE.. LOL, Time for a SA meeting. Stereo's Anonymous

Maybe a

For the RtR, I promise I'll quit, just this one last time.. :-) The flame get hotter.  

BUT BUT It's a retirement present from, from, from, Someone!!!!

I'm glad God, the rabbit and the dog loves me, because the wife sure isn't.. LOL

I’m not a cable guy, but I do try to go a few steps up the ladder from standard computer peripherals.  I think most of the improvements in cables come from those first few steps and then you are into diminishing returns.  Personally I don’t hear a difference in Ethernet from CAT 5 to CAT 7, but I do hear a slight improvement with usb cables.  I like the Pangea line from Audio Advisor 
With CAT8 each conductor is individually shielded. Lower noise, protection from RFI/EMI. 
Regarding Ethernet (presumably to a server or streamer), there are several choices to make,
  • should you use a CAT cable or fiber optic cable
  • which CAT cable to use (i.e., 5e, 6, 7, or 8), 
  • will a CAT cable that is advertised as being intended for audio systems provide improved performance in some way over a generic CAT cable with the same designation, and then
  • if you believe the above, which "audiophile" CAT cable will you purchase
I suggest first reading about the specific differences between CAT cables from sources like this one, or this one.  For transmitting data in a residential setting, virtually any commonly used CAT cable should do the job relative to bandwidth, data rate, and speed, so the differences in their abilities to reject EMI/RFI and crosstalk may be more pertinent features to look at.  You may also want to look at opinions discussing why audio-specific cables may offer improvements over more generic cables, like here or here.

Regarding USB cables, Belkin Gold is one of the best-regarded of the inexpensive OTS options, and many don't see the need to pay for more.  OTOH, many audiophiles report hearing differences between USB cables.  Supra makes a relatively inexpensive USB cable intended for audio that has been favorably reviewed, and prices go up from there with audiophile USB cables ranging in price from several hundred to several thousand dollars.  You may want to search articles discussing USB cable comparisons (like this one) to help you decide where you want to land on the spectrum.

Everybody hears this stuff differently in their own systems and with their own ears.  I settled on a relatively good quality OTS CAT 8 Ethernet cable for my 45-foot run but then switched to fiber, resulting in only a small (negligible?) perceived improvement in sound.  I do seem to perceive differences in USB cables but happily settled on TWL's $330 “Split Power & Data” USB Cable, after trying several.  However, to my ears, none of them changed the basic sonic signature of my system.

It‘s not just the quality of cables, it is also majorly their length. This applies particularly to USB where RFI/EMI incursion is a major problem. For what it‘s worth, I had major benefits from using a short (25cm) Intona Reference cable between server and dac and a short Meicord Ethernet cable between filter and streamer.
Absolutely I had both, my Bricasti is both a very good dac,and streamer the Ethernet  cable has a lower noise floor.
that being said ethernet,or usb the New Wireworld Platinum 8
is a outstanding cable that truly brings out added detail and musicality, highly recommended 1m minimum .
After much ’messing about’ with cables my conclusion was: for long runs optical is best followed by cat 8 down to cat 5. I did not try Hifi quality for this section as the run is 20 meters. For shorter runs I found small differences between cables. There are some very good Hifi quality less expensive cables around. 
For USB there are significant sonic differences, and shorter lengths definitely improves the sound. A friend of mine makes his own and a 20cm cable of his were amongst the best, competing with multi hundred $ cables. In his design he closes off the fifth pin in the usb, the one delivering 5v power - if your DAC does not require any power from the USB, and many don’t, he finds this helps reduce noise from the cable. If your DAC does use the fifth contact oin then this cable won’t work. 
You can actually do this with any usb cable - simply tape over the right hand pin on one end. It’s an easy test and you might hear a difference.
Kind of odd that the OP claims he has good cables between his other components but is asking if good cables matter to a server. Any good quality component can benefit from better cables, especially a source component 
Bits is bits as they say.
Put in any old cable.  Measure the error rate.
It will max at about 2 or 3 per million.
The other 999,998 will come through perfectly.
You can't hear the two that don't.

End of answer, apart from dither and clock error that are not products of cable, so far as I know.
p05129 what may seem odd to you is not to others. My claim to have some good cables is based out trying different ones but, I haven’t tried other USB or Ethernet cables. I was hoping to minimize that process and I thank everyone who has helped by sharing their experiences. This is a great forum because I’m getting feedback from so many audio fans.
I haven’t tried super high end Ethernet cables but can confirm that Supra cable is a clear and wonderful enhancement over generic Amazon cable. And it’s cheap as far as cables go (I think 55ish for a short length).

I have more than I need so will be listing here or the Mart when I get around to it.

for the umptiest time: it isn’t the errors in bit transmission but rather spurious EMI/RFI or ground level noise travelling alongside the bits and messing up the d/a conversion that good cables can address. 
I don’t find it odd at all that the OP would like to verify Ethernet and USB make a difference. I always hope I don’t have to go through the expense and effort of selecting a high end cable for something. I keep hoping this time it will not matter. 
Unfortunately, once again it does. I just put in a second direct line just for my amp… damn, it mattered. For once I would really like it to not matter… this gets expensive and time consuming.