“Does the use of 48-volt phantom power affect the performance of the shield on a microphone cable?”
Resistors generally limit the current that is typically drawn by a phantom-powered condenser microphone. Therefore, this is not a significant factor unless the shield begins to break down mechanically due to use. Tearing or fraying is possible, which could create intermittent changes in shield resistance. This has lead some professionals to prefer the use of three-conductor microphone cables, with the common carried by a drain wire in addition to the shield.