My worst experiences with noise were during World Expo 88 in Brisbane.

The first was with the new you-beaut latest model 32 band stereo graphic equalisers that were in use everywhere and used a proprietary chip that often went noisy. I must have replaced at least 100 of those 12 pin inline goop encased sub-boards that held the chip which for nil obvious reason would randomly simply start generating higher levels of hiss that was not unlike a reverse biased diode.

The second was the Soundcraft 40ch/16bus foldback console on the river stage. The sound guys and the artists all complained about the poor noise floor while doing shows, so we contacted Soundcraft in the UK. They were very nice yet somewhat apprehensive when they advised of a modification that could be done to this $150k console. Ultimately after many phone calls and various assurances I performed the modification which involved a number of wire and solder changes and taking a dremmel to every board in the desk... I had a 11hr window to do the work which took 9hrs with the dremmel and all the while in the back of my head I knew that this one desk was worth more at the time than most inner city Brisbane CBD apartments, plus the desk had to be back in service by 10am.... The mod worked fine but it was Yay, and team me totally stressed out and dead dog tired by the end...

A side note of trivia - my avatar is a pic of some Gold Silk embroidery on a Black denim jacket I had done at the China pavilion during the Expo...