Sounds like you found the problem, but to answer your question, YES... a tube could have blown. The 834P uses two 12AX7's for left and right channel gain.
Left channel produces NO sound.......Help needed
I have an Ear 834p phono pre. I discovered that my left channel produces no sound. All connections are secure.When I play my cdp I get normal sound from both speakers. Could a tube have blown in the Ear unit? I have never owned tube gear prior to this phono pre. It's not but six months old and hasn't had a tremendous amount of use. Any and all suggestions would be appreciated.