hey fellas.

i have had an mbox for a few months, though it is barely used bc i am so busy. i have several mics, most of which i use for my perfroming groups (Shure SM7, Beta 58, Sennheiser e836 and two RODE nt3's). now i have used each mic with the mbox for fun until i can get a better condenser. the sm7 is a bit dark for my tastes with recording my voice. i have had no noise issues with any of the mics but the two nt3s. there is a high pitched sound whenever i turn on the phantom power either on the mbox or on the mic if using the none volt battery. now since it does it on both mics. is it safe to think i have a defective mbox? it is really brand new so i would be surprised but do i need to contact Digidesign asap? how long are their warranties? thanks guys/.