Found the spec in the X32 Wiki:
https://behringerwiki.musictribe.com/index.php?title=X32_RACK%3A_AES50_cabling_requirements
Summary:
Shielded Cat-5e cables only
Ethercon terminated cable ends
Maximum cable length 100 meters (300 feet)
That is Behringer/Music Tribe's interpretation of the Standard, which is an AES document and sets the fundamental terms for equipment that is built to be compatible with/meet the Standard. It is downloadable for free by AES members from
the Standards section of the AES Member Portal . It is a copyrighted document and is not printable or even quotable here, per the agreement that is made by Members when accessing the Standards.
It does in fact say "or better" or "or higher" after naming the CAT level (5 or 5e). It specifically does not say to only use 5e or that only 5e CAN be successfully used.
Behringer/Music Tribe's take on it does not change what it says.
5e has proven sufficient for many people, although the construction of 6a cables make them more resistant to certain kinds of problems (handling and sync loss issues, primarily IMO), while 5e's most common constructions do not have that same resistance.
The STP 5e that Behringer sells seems to be adequate on all levels electrical and construction, and while that is certainly what they want you to buy and use, they only sell one length (50 meters). You need to figure it out for yourself if you need longer or shorter, and all 5e's are not equal in all respects.
I do agree that many people will be mostly fine most of the time with most 5e's. It's those other times that will visit the gremlins upon you and make you want to figure out why there is a problem. Sometimes going to the higher cable will resolve those problems, even though the needed bandwidth would not seem to require meeting the higher standard. The issues needing to be resolved do not always involve bandwidth. Shielding and Ethercons are examples of that.
EDIT:
Thanks to Luke's simultaneously late and timely posting in the other relevant thread, I see that I violated all protocol and posted in that thread the relevant text of the Standard there, which is:
====================
"4 Physical Interface 4.1 Physical medium
"HRMAI uses a four-pair twisted pair data cable. The minimum specification shall be Category 5 as defined by TIA/EIA-568-B.2, although the use of more stringently-specified cable such as Category 6 is recommended.
"The use of screened (shielded) twisted pair (STP) cable is recommended."
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So my memory in the upper part of this post preserves the spirit but not the actual wording of the Standard. That's probably the best that can be hoped for from this old brain.
