ETHERNET CABLESFirst up, by popular choice (

), is ethernet cables.
Almost all of the Cat 5e, 6, and 6a were UTP. The only S/STP was the Cat 6a.
The setup was as follows:
iMac w/Roon <----ethernet----->
Switch <-----ethernet----->
BDP-1I would use the spare Linksys E3000 router initially to get these unmanaged switch working and connected to each other. Once the BDP-1 was recognized on the Mac, I would unplug the router and its power supply. No other devices were present on the switch. Only 2 ethernet cables at a time. No other switching power supplies besides the bare essential for the audio networking.
All the audio gear on Torus. The stock power supplies for the router and switch on separate strip outside the Torus. I kept the distance between all the gear and path of the cables constant.
The Cat 6a SSTP came with graphs and readouts as well. Each cable had the propagation delay (ns), delay skew (ns), resistance, and other performance characteristics measured individually.
Sound:Used HD 800 and all Amphion monitors/amps/cables monitor setup.
Cat 5e and 6 UTP:-All the Cat 5e UTP sounded the same.
- All the Cat 6 and 6a UTP sounded the same.
- The only tiny difference I felt at times between 5e UTP and 6 UTP was that the cat 6 had a tiny bit better focus. Still, nothing compared to other tweaks.
- Sound tonality and presentation was the exact same.
Cat6a S/STP:- These came with metal plugs on both ends.
- The BDP-1 has shielded ports.
- With the DGS-1005 (unshielded) and DGS-108 (shielded), I could try connections where the grounds would be attached on both ends or only one end.
- In a home environment, I could not ground the DGS-108 switch
- Eventually, I even took out the metal shields on both ends, which allows me to verify whether what I was hearing was due to any differences between the switches and their power supplies.
- I would NOT recommend having the grounds connected on both ends when both devices have shielded ports.
- In general, I would not recommend having the ground connected on the BDP-1 end.
- I eventually had the ground disconnected on both ends.
- I did find that the Cat 6a S/STP had the blackest background among the bunch and this stayed regardless of whether the grounds were connected or not on one or both sides.
- When you have one or both the grounds connected, there is a specific characteristic change to the sound.
- I felt this character was really exemplified when grounds were connected on both ends.
- The transients were oversmoothed and this was noticeable on material with a lot of drums and kicks.
- I compared my 5e UTP, 6 and 6a SSTP with the ground lifted to the ground connected 6a cables. The former all presented drums and kicks with clean rise and decay. They all sounded correct this way.
- With the ground connected, the drums didn't have the proper energy and bite.
- There were other changes I noticed and to some they may or may not like it.
- I just knew that the sound wasn't correct and so ditched the shields on both end. Better this way for me.
- With the shield disconnected on both end on both pair of Cat6a S/STP, this is where I found the sound was the best.
- Clean transients and correct sound like the rest of the UTP, but with better clarity and focus to the image and a black background.
- There can be a number of reasons for why there might be a difference.
- The Cat 6a S/STP not only eliminates pair to pair crosstalk, but is also better suited EMI/RFI wise in an audio environment in rejecting or radiating noise.
- This can reduce interactions with other nearby cables and gear.
Two useful links:https://www.siemon.com/us/standards/Screened_and_Shielded_Guide_9_Why_Use_Fully_Shielded_Cabling.asphttps://www.siemon.com/us/standards/Screened_and_Shielded_Guide_7_Antenna_Myth.aspTL; DR: - If going with UTP, go with Cat 6 and forget about it.
- No sound difference between any of the Cat 5e and Cat 6 UTP cables.
- For best sound, go with a S/STP design, but make sure that the grounds are not connected.
- Introducing the ground can change the sound in a very specific manner (softened transients, over smoothed sound)
- Shield and screened cables can potentially offer a very quiet background, and better clarity. You can read up on the phase performance of both the HD 800 and Amphion monitors.
- YMMV based on your environment and setup.