limits of interconnect length?

My hi-fi speakers sit either side of my TV although the hi-fi hardware is off to one side. I have a spare input on my preamp so thought about connecting the TV to run its sound through the hi-fi. To keep the interconnect unobtrusive I'd need around a 5metre length. Are there any technical issues (like nobody makes them) in fitting interconnects of such length? It would be phono to DIN or phono to phono through an adaptor into my NAC 82. Any advice gratefully received.