If phantom power on a mixer bad for a separate mic preamp?

a tube mic has it's own preamp unit that has like a 6 pin input from the mic, and XLR output to the microphone. i have other microphones that require phantom power and have no external preamps, so i use the mixer's phantom power. would this be hazardous to the external preamp of the tube mic? i thinking it wouldn't be since the ouput is balanced. . .