I'm doing some acoustic guitar tracks with my U87 in studio today (in control room where monitors are there) and I forgot to mute the monitors when hitting the record button and it cause a really loud high frequency feedback...

I would like to know if it will hurt the mic or mic pre? I'm use NON TUBE mic pre:

http://davehilldesigns.com/EUROPA_1.html

Your respond is greatly appreciated. Thanks!!