Just seen this on a fBook thread:
"I was just playing on my studio, as usual, suddenly I hear a few loud pops. a few minutes later, again but much worse and for longer, I look at the CQ-18T screen and it was like all the channels had very loud inputs and the screen was flickering..."
Those symptoms seem pretty identical to what I've been getting. Which is kinda worrying that this might be a design flaw. However, he did follow up with this:
"Update - I think I've found the issue!! I've moved some cables recently and I left one of the outputs cables running in parallel to a power cable. Once I re-organized the cables it didn't happen again."
No idea what he meant by "running in parallel to a power cable" or whether that gives any wiser folk than me a clue as to what might be the cause?