To make a long story short, I had the ribbon cables removed and the connections hard-wired (cost = $250).
Apparently the plastic connectors at the free end of the cables sometimes come loose from the pins they fit over. The suggested solution - bending the pins apart to produce a tighter connection - did not work for me. I also discovered that it would take a longer period of time to replace the cables than I was willing to wait, and that I could not be guaranteed that the replacements would not develop the same problem.
The improvement, and I don't just mean solving the channel drop-out problem, is extraordinary. I don't know if this would improve the sound of a 5350 that works perfectly as intended (I do not have a new 5350 to compare my amp to, so this is entirely from memory), but all I can tell you is that I believe the amp now sounds significantly better than new.
As for the use of ribbon cables in an amp to carry analog signals, there seems to be quite a bit about the subject on the web. Owners of this amp can examine that issue for themselves and draw their own conclusions.
Once again, the sound of this amp is now beyond anything I expected and quite extraordinary.
Apparently the plastic connectors at the free end of the cables sometimes come loose from the pins they fit over. The suggested solution - bending the pins apart to produce a tighter connection - did not work for me. I also discovered that it would take a longer period of time to replace the cables than I was willing to wait, and that I could not be guaranteed that the replacements would not develop the same problem.
The improvement, and I don't just mean solving the channel drop-out problem, is extraordinary. I don't know if this would improve the sound of a 5350 that works perfectly as intended (I do not have a new 5350 to compare my amp to, so this is entirely from memory), but all I can tell you is that I believe the amp now sounds significantly better than new.
As for the use of ribbon cables in an amp to carry analog signals, there seems to be quite a bit about the subject on the web. Owners of this amp can examine that issue for themselves and draw their own conclusions.
Once again, the sound of this amp is now beyond anything I expected and quite extraordinary.