Cables and interconnects do sound different. Putting aside the value discussion, because that is a personal decision, I do certainly hear differences. Much depends on the transparency of the chain. If the other components are very transparent, and capable of full-bandwidth performance, those differences and improvements will be more audible.
As an example, with a system consisting of a Pioneer receiver and Klipsch RP-600M stand mounts, the Synergistic Research Foundation Series speaker cables will not produce as dramatic an improvement as compared to, say Parasound JC1+ driving Magico S5. The second setup is so much more transparent and capable, the improvements yielded by the Foundation cables over other less-capable ones will be clear and present.
As an example, with a system consisting of a Pioneer receiver and Klipsch RP-600M stand mounts, the Synergistic Research Foundation Series speaker cables will not produce as dramatic an improvement as compared to, say Parasound JC1+ driving Magico S5. The second setup is so much more transparent and capable, the improvements yielded by the Foundation cables over other less-capable ones will be clear and present.