I wouldn't use metal conduit. You should use plastic. If you use metal, then you need to ground it properly and may end up with ground loop hum, too- what a mess. Just use plastic conduit and you can avoid any potential problem. As far as cables you should a least buy something with silver-coated copper core (versus bare copper of the Belding) and perhaps more important a cable with a teflon dielectric material - that polyprop in the beldings may work okay for a long component video run, but for a long run of audio interconnect I'd go with at least a silvercoated fine standed copper core wire with teflon dielectric - and 95% copper (or tinned copper) shielding and teflon outer jacket.