Anyone Using The G5's S/pdif Port? Options

[the clash]

Anyone using the G5's S/PDIF port with a Vox Tonelab's S/PDIF port?

Im thinking of buying the Vox Tonelab for recording guitar and just wondered if anyone had hooked it up to a PowerMac G5 via the ToneLab's Digital Out S/PDIF and into the G5's Digital In S/PDIF ports?
Is this do-able?

Not heard anyone do this as it always seems to be Firewire & USB that people mostly use. Would using a S/PDIF port be any better than using a Firewire port?
Cheers.