Hello Kjetil and welcome to the Cow Audio Forum,
I have a G5, but there are a number of different versions.
I’m not sure what you’re trying to do, bring stereo digital audio into your G5 Mac through the optical SPDIF port for what purpose? Not all applications will be able to use that port for input. The ones you use may.
What noise? Internal fans cause mechanical noise. That shouldn’t be any problem with an optical input. There were some noise issues on the firewire ground bus due to a poorly designed power supply in some G5 Macs. I had one and Apple replaced it.
As to which converter is better, it’s hard to say. I use the optical input for the output of my CD recorder. That lets me play the CDs though the G5 and out the G5 unbalanced analog ports.
Regards,
Ty Ford
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