I received this email response from a dealer:
Interconnect cables can be either RCA single-ended style or XLR balanced types. The XLR balanced type reduce the noise character and have negligible signal degradation over length. So these would be the preferred cable whenever possible regardless of length, when connecting source components, preamps and amplifiers.
RCA single-ended types are prone to noise pick-up whether from electromagnetic interference or from radio frequency interference and will have high frequency degradation once over 6 feet in length. If you have no choice but to use this style, keep the lengths closer to 3 feet if at all possible.
The least signal degradation will be associated with speaker cables since these are carrying a higher power signal where effects of resistance, capacitance and inductance are easily overcome with the stronger signal. If there is a choice between longer interconnects versus speaker cables. choose the longer speaker cables for better results.