spdif & IR repeater on cat 5 help

[hairyben]

Hi, need to run a digital audio feed and have a cat 5 of about 8 meters in place of which two pairs are utilized for IR repeater

PoS samsung TV as well as having no ARC on HDMI1.4 also only has toslink out, so can I use a pair for SPDIF, and would using one remaining pair for SPDIF and the other to supply DC to a toslink/spdif converter box cause crosstalk issues?

Failing this another cat 5 that could be pushed into service is the one with a pair in use for sub feed

Thanks.