Following up on my previous posts about the resistor value non-issue, I've found myself sufficiently captivated by all of this unfolding drama to complete a careful look at all of the photos at Rebbi's blog, looking for anything that might account for the problem.
I found nothing. As might be expected, everything looks to have been done meticulously and accurately. I even checked all resistor values against the schematics which are available on the Internet, with the exception of the four resistors on the filament supply board (those don't seem to appear on any of the schematics I found; apparently they were introduced during a relatively recent revision of the design).
I did note what MIGHT be a bit of heat damage on R21 of the driver board, but looking at the schematic I don't see how that could account for the specific symptoms in this case. And in any event that resistor would only affect one channel.
One possibility that seems very remote but I wouldn't totally rule out at this point is that the output transformers were manufactured with the wrong color coding on the wires. I say that in part because most (but not all) versions of the Kit 1 for which photos appear on the net have transformers which used a different set of colors for their secondaries than the green-blue-yellow colors of the ones that were supplied to Rebbi. And of course if the colors were mixed up such that the 4 ohm tap is being used, or the speaker connections are being made BETWEEN the 4 ohm and 8 ohm taps, that would easily account for the problem. The tech could probably verify the color coding by measuring resistances between the different possible combinations of the three wires.
Best regards,
-- Al
