Are you sure the 'GISO GB LAN/AES/EBU isolation for studio use' link was correct - that page stated you cannot use it for AES/EBU without adapters.

'GISO can also be used for AES/EBU signals using suitable adapter cables'

This actually means it's less convenient than XLR - since you'd need 1+1/4 unit to actually isolate the SpeakerLink signals.

You can't feed in the SpeakerLink signals blind and assume it works (if it does it's not actually doing anything - especially if the DC power from the SpeakerLink makes it's way through) and having RS232 RX+TX going through one transformer would not achieve much.

To isolate SpeakerLink - surely you need 5 transformers? (5 pairs of wires - that isolator only does 4 pairs)

1 TX - SpeakerLink data (AES/EBU) +/- (no ground reference needed)
1 TX - RS232 Transmit + ground
1 TX - RS232 Receive + ground
1 TX - Master Comms + ground
1 TX - Slave Comms + ground

(Someone please correct me if I'm wrong - yes I know you could probably leave one set of signals out if you don't want to call it SpeakerLink anymore - also - how does the DC power-over-SpeakerLink work?)

Since some people believe changing the digital interconnect changes the sound, surely throwing in a bunch of adapter cables to adapt from RJ45 SpeakerLink to RJ45 wired-for-lan, the transformers and another bunch of adapters would also degrade it?

I've left out any mention of the frequencies / voltage levels / differing impedances / the other sciency words etc... - and just gone for the physical issues.

At least with older Allen-Bradley PLC's, the 24V power line on the RJ45 serial ports tends to educate people very quickly the difference between an RJ45 socket and a LAN connector.

Matt.