Beloved [Mission] and Healthy Cyrus One Amp - advice neede..

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Hi,

I have a Mission Cyrus One amp (this is relevant to the Two model
also) which has suffered in the past from a blown output stage. That
day I turned the amp on one after listening (at low volume) the
previous day, and one of the outputs just wasn't there from power up.

The retailer shipped it back and it was repaired (replacement Output
transistors) and all is fine.

After a few years the same thing happened again (can't remember if it
was the same channel but this time it suffered a continuous hum on one
channel). Once again it was fixed.

Looking on the internet it seems this is a common fault. I have
previously read that this may possibly [italics] be down to:

- the 'record' and 'listen' rotary switches set to the same device
- either 'record' or 'listen' set to 'mute' whilst receiving a signal
- the onboard power switch causing a spike
- something completely different

In the advent of time I now have no need for the record setting so I
would like to just set it to something and leave it.

So my big question is how do I prevent this problem from re-occuring.
Is it down to a specific event or is it something which is a problem
with the circuit design which can become unstable.

Your thoughts would be gratefully accepted.