Wow, I'm glad I came across your thread.  The exact same thing happened to me... twice.   I had 600 ohm DT880s, which I used for a month while I waited for my WA3 amp to arrive.  Received the WA3, plugged them in, and the second time I used them, there was a little spark in the power tube...

After reading quite a bit on these forums, I finally decided to purchase Beyerdynamic HD880/600ohm with a woo audio 3 amplifier. I have my source connected to a fireaudio spitfire DAC, which then feeds the WA3. I just hooked up the amp today. The problem is, I get almost no sound out of the...