Hi. Cables for low-impedance balanced microphones (driving balanced preamp or recorder inputs with 1000+ Ohm input impedance) can usually be several hundred feet long with no audible problem.
The main determining factors are the capacitance of the cable (in pF per foot or per meter between the two modulation leads), the output impedance of the microphone, and whether or not the microphone has a transformerless output circuit. For driving long cables a transformerless output is greatly preferable, with as low an output impedance as possible.
If the cables are too long or have excessive capacitance, you can run into high-frequency losses. For microphones with output transformers there can also be a reduction in headroom (maximum undistorted sound pressure level) at high frequencies--or conversely, excessive distortion when trying to use the microphones at levels of high frequency sound that would be OK with cables of more ordinary length.
--best regards