My experience matches your. My first pair of Royal Princess 300B tubes had a tube failure in less than 3 months of light use. The replacement pair were extremely microphonic. They rang like bells when tapped lightly with my fingernail. I was told that it needed to be broken in. (Or how long do you think Ive been stupid?) Of course, they were still microphonic after breakin. Reporting no improvement, I was told, "Stop tapping the tube." I would never recommend Sophia, especially hearing the experience is not unique.
BTW, their 300B is good but its not a Western Electric. The Westerns won hands own in my system shoot out.
BTW, their 300B is good but its not a Western Electric. The Westerns won hands own in my system shoot out.