Source of a NP 47µF 60+V capacitor for audio?
Okay, 


low-ESR: Low ESR in a coupling capacitor is umm.. not very important, especially for audio. Leakage may be worth considering (especially if the leakage contributes noise). The conductive polymer caps are very leaky in comparison to cheap aluminum electrolytics. 
Non-polarized: Phantom power has only one polarity, so you can orient the caps appropriately. As it turns out, all e-caps are non polarized for very low voltages. 


Without seeing the circuit it's hard to tell, but I would think any high quality low-leakage polarized aluminum capacitor would be indistinguishable from the best capacitors you could buy.