Impact of low quality analog RCA interconnects

Hi,

What is the most common sonic impact one would expect by using lower quality RCA interconnect between dac and preamp vs high quality ones?

I'm thinking about replacing radiobshack interconnects with higher quality chord to address an occassional sibilance, high frequency/ treble harshness problem ( especially on live recordings of female vocals)? Any this will solve my problem, or is it a dac issue?

Jf