I had a day like that last week. So many things didn't work right that I considered going back to bed.
One of those things was a new hiss in my speakers. My new QSCs that I love, partly because they're so quiet. Turned off the mixer, the hiss diminished but was still unacceptably loud. I began to panic. Do I still have the shipping cartons they came in? Should I tear them down myself or send them to the factory? What will QSC charge me for a new amplifier module? If I take them apart or send them away, what am I going to use for this weekend's gig?
Then I walked around to the back of the speaker and discovered that the volume control had been bumped in transport after the previous gig and was set to its maximum rotation. Brought it back to 12 o'clock where I normally run it and all was well.
Then I sat down with a sense of relief and pulled up SONAR. There was a crackling noise in the right speaker. My treasured Emotivas. I began to panic. Do I still have the shipping cartons they came in? Should I tear them down myself or send them to the factory? What will Emotiva charge me for a new amplifier module? Do I even want to keep these speakers if the quality is so poor that they fail in less than a year?
Then I swapped the left and right XLR cables. The crackling moved to the other side. I remembered that I'd bought these TRS-to-XLR cables from PartsExpress.com because they were ten bucks apiece, so if they worked out it would be a great bargain and a great source for future cable purchases. I'd forgotten that I'd been dubious, forgotten it was an experiment. Replaced the cables, and all was well again. Note to self: ten-dollar cables are like marked-down tuna sandwiches; ya takes yer chances.