Is an I2S cable a Cat 5, 6 or 7 Ethernet cable, or are they two different beasts?

I2S is the protocol used within a DAC for moving data from point to point.  There are some devices that can transmit data in this form and DACs that will accept it in that form.  Doing so avoids two steps of data conversion and can lead to better sound.  PS Audio and Wyred 4 Sound are a couple of manufacturers that come to mind that use this.  For both of those manufacturers they use a standard HDMI cable to transmit the data.  CAT 5/6/7 are all Ethernet data cables for transmission of data between computers, completely different from I2S.

Ahendler, if the manufacturer uses an RJ45 connector for outputting/inputting their I2S data, then yes you can use a CAT 5/6/7 cable. Otherwise, no you can't, the connectors are incompatible.  Could you use CAT 5/6/7 wire with an HDMI connector?  Maybe.  CAT 5/6/7 has 8 conducting wires, and HDMI cable has 19, but when used in the I2S application I don't think they use anywhere near 19 wires to transmit the data.  Not sure why someone would do this, but it could be done.

Ahendler, I stand corrected!  Never heard of using an RJ45 connector for that purpose, but now I know at least one does.  Not sure what source uses the RJ45, didn't see one on the Audio GD site, but must be at least one.  I will say a lot of people get confused by the HDMI connector thinking it is an HDMI connection when it is not.  Same problem with an RJ45 and computer networks, hopefully no damage occurs when improperly hooked up.