Years ago, I owned a D-250 Servo. After a few months, with not that many hours on the stock ARC 'selected' tubes, a loud dramatic explosion occurred with smoke, etc. I had to send "Big Bertha" back to Minnesota for repairs. When it returned, I sold it.
I own a pair of M-100's and a custom modified D-79A. I've never had any problems with them at all. They have individual tube bias. I've retubed them with reasonably priced tubes from reliable sources.
I own a pair of M-100's and a custom modified D-79A. I've never had any problems with them at all. They have individual tube bias. I've retubed them with reasonably priced tubes from reliable sources.