Wow Gents! I didn't expect this kind of response. Lots of venom being sprayed about. But at least it got you all thinking about the problem.
I went over for a visit today, and the left Audio Research Mono Block Amplifier is still dead, as my friend just recently found a "local" authorized repair person certified by AR. (In the past he packaged them up and sent them back east to AR in the USA.) The repair guy lives in Edmonton, and vacations in the Gulf Islands here in BC; so he will pick it up on his next trip west in a month or so.
In all of the failures AR said it could not identity what was causing the issue. On 12 of the failures the input was the turntable, and two were the Mark Levinson CD Transport. So it's not consistent based on input. I've got photos but can't up them here so I found links to existing pics around the web.
My friend babies this system an would never unplug cables when energized. He warms up the system for a few minutes before listening to anything. It's quite a ritual when he does it. He was talking to his security technician (he's got about 30 wireless cameras all over his property) and he suggested the RF from those devices may be causing the problem. I don't see how as everything is shielded but what do you think?
Speaker Cables are CV Terminator Twin MH-770 like the photo below but they don't have Tube on them. I think the left one was weeping something out from a screw on the back. (I assumed it was a capacitor failing but I don't know what's inside these things.) I'm trying to convince my friend to removed these and try "regular" cables once the Amp is repaired. I think this would be the easiest item to eliminate.
My friend is one of those convinced the MIT Cables work. His vendor sold a few systems like his when he bought his (mostly to Russian Mafia types he said) and not one had any issues.
Here's what the Speakers look like:
And the AR Amp:
Here's the manual (such as it is)
http://www.audioresearch.com/ContentsFiles/REF600 Manual.pdf
Any help would be appreciated.
Thanks for the assist.