Will a RCA to RCA adapter hurt the sound?

I have used gold plated RCA adapters from Radioshack to join 2 of the same cable to make longer cables and never experienced any sound degradation. How long though are you going to extend the cable? IME with using adapters I've only extended cables to either extend the length of my turntable cables, or from preamp to amp which was just another 3-4 feet of wire. Those were the times when I had no sound issues. Another time I used these adapters to extend the length of my subwoofer cable and had no issues there either. I joined 2 6ft cables.

Before you move your rack, listen to your kit with the single RCA cable that you presently have in place, establish a sonic reference. Than try adding the additional RCA and adapter... and listen again. Repeat if necessary. Then do what you have to do.

In theory, everything counts, every interconnection becomes a bit of a degrade. In the extreme, in practice, audiophiles have been known to hard solder patch lines from one component to another with huge gains in overall transparency (that's right, no IC's), though impractical for most of us, it is a cleaner, simpler path.

Let your ears be the final judge.

Happy Listening!

If you're not purist and crazy about it, than it shouldn't. 

I don’t think that anyone can say with any certainty, so the experiment suggested by R_F_Sayles would seem to be worthwhile. FWIW, though, my guess is that **if** a difference results it is more likely to be caused by the added length than by the adapter. Depending, that is, on the output impedance of the component driving the cable, the lengths that are involved, the susceptibility of the interconnected components to ground loop issues (ground loop issues can be sensitive to the resistance of the return conductor in an interconnect, and therefore to the length of the cable), and other variables.

I assume, btw, that you are referring to line-level analog interconnects.  Not to phono cables or digital interconnects, for which I would recommend against using an adapter.

Regards,
-- Al