Help Loud pop when muting BAT VK-3i preamp

Hey guys! I just got a BAT VK-3i installed in my work-in-progress listening room. I had the guy still in the box for a few days, but wanted to wait until I got my dedicated lines installed to fire her up.

NOW...

There seems to be one small problem with the mute function. Whenever I press mute on either the remote or the front panel of the unit, I hear a very loud "pop!" from the left speaker (Magnepan MMG), primarily (maybe there is something in the right speaker, but I cannot hear it over the very loud pop in the right speaker). Also, when I turn the volume down to "00" I get the pop (because the muting is engaged) and when I power the unit on, after the tube heath 60sec check-up/delay I get the pop again. Now, I've rotated out my amplifier, my speakers, the interconnect between the amp and preamp and I had the "pop!" with every iteration. Also, it does this even if no source is playing (or even turned on) and also even if I select a source via the knob that I have nothing hooked up to. Therefore, it cannot be the source or anything upstream of the preamp. The only thing I haven't changed is the speaker wire (Kimber 4PR). I am going to put my old preamp back inline today and I expect that the pop will go away. Do you think this could be a bad tube? I figured I should probably talk with BAT on Monday, but I just got finished e-mailing this to the seller here on Audiogon and I wanted to post a similar reply to the forum to see if anyone might be able to help.

Thanks!
-Marc