Is your ADA MT-100 (Microtube 100) only workin in one channel? Try this

[Dante]

As much as I hate to say this, it's a common problem with these amps. But, do not despair, it's an easy fix!

See this thread

Some cheap parts and some solder skills should put you back in the driver's seat (parts list below}

[Harley Hexxe]

Now if we could only figure out the cause and fix it, that would be great!

[Dante]

Yeah, if something else is FUBAR, maybe those transistors won't get fried. My question is; which two run channel B? I would only have to change two instead of four parts.

I guess that's another reason to change one part, and then check