you may try powering the camera with DC volts instead. That means, using an external power supply to travel the voltage through the blue or brown pairs (splitter concept). That should work fine if the distance between the camera and the nvr is considerable short (<50FT). In that case, the extra pair could be used for audio (for example, the blue pair). For longer distances, if a power outlet is available near the camera location, you may power the camera directly, while using the extra pairs for audio/relay. Even thou the twisted pairs will help, you should test for the audio signal/noise generated over long distances. A balun impedance matching could help for transmitting audio signal
