Thanks for all the advice guys! The reduced volume issue seems to have been fixed. Even with the new buzz, vocals and instruments seemed to be more balanced. I didn't have to really fab anything for the main filter caps except for the standoff. I DO have a meter with continuity mode. So, I will dig in and anyalyze more with that. I checked the solder joints of all the new caps and they are identical to the original joints. Not shiny, but they don't appear cold. They appear to be solid and I also verified continuity of all leads to adjacent components on the same trace. These boards are really stout. I don't think I overheated anything and certainly didn't overheat traces. So, I'm fairly confident there (unless there's something else I need to check). Thank you. As for polarity, just to confirm....all of the negatives have a solid block printed on the top side of the board to indicate neg, correct? That is how I installed them. (also referred to how the original cap was installed, but it's possible to make a mistake). At one point, I panic'd thinking I had installed the filter caps wrong, but brown wires are positive and blue wires are negative . I did reinstall the original filter caps and that had no affect. I think you guys are correct that perhaps I broke a connection loose when moving the boards around. The multi-color harnesses with the white connectors are very tight until you snip the zip ties holding them to the main harnesses. Although the connectors probably got pulled a bit, I don't see any evidence of broken solder joints. I was very careful not to overheat. I think I had the iron on at the right temp and was holding the cap on the other side of the board as I soldered. Never got too hot. Would a board-mount transistor cause a buzz, or are we pretty sure that I'm chasing a bad ground? I will try to post some pics tonight. One more thing I noticed, why does the LH pre-driver board have a safety cap from the B+ to ground and not the RH board?