I tell you, I had it happen today with my CDP. Scared the hell out of me. First I thought it was due to me installing my "Porter Port" outlet incorrectly. No, it is to straightforward to install an outlet. Did some reading here on A'gon and determined it was static electricity. I had jumped off my couch, with just socks on, my feet that is, slid across my carpet on my knees, and touched my CDP. All of the sudden, a loud electrical noise came out of my speakers. Anyway, use a humidifier, and find some antistatic spray. You also want to make sure you touch some other metal before touching your DAC. I think there is a joke in that last sentence somewhere but I will not go there.
Matty
Matty