I’m not sure I understand this. In this latest experiment was it the speaker cables that were switched (per Yogiboy’s suggestion), or the interconnect cables (as seems to be implied when you said "the right channel is supplying the left amp")? Or was it both that were switched?
Also, previously you had found that switching the interconnect cables after a few minutes had fixed the problem. And that leaving the preamp in standby when it was not being used also eliminated the problem. And that popping had been heard in both channels. Not sure how to reconcile all of this.
Perhaps two problems are present. Or perhaps the preamp is the only problem, but its condition has worsened to the point that both channels are now affected in a similar manner, and the preamp is intermittently injecting either DC or some transient from its right channel output that is causing the left channel amp to which it was apparently connected during this latest experiment to shut down.
It all seems very inconsistent. But in any event I would not conclude at this point that the amp is necessarily the only problem, or even that it necessarily has a problem.
Best regards,
-- Al
