I'm designing an audio mixer and currently i'm working on a cue section. The whole point is that i have 2 or more channels and want to mix them in summing mixer. You can turn off the channels you don't want to hear - simple switch -> ground the channel you don't want to hear or connect it to the summing resistor.
When i turn off the channel the summing resistor is floating. Floating input of an op amp is usually not a good idea. Putting relays that ground the floating inputs when unused sounds like a lot of hassle. Any other ideas? Or maybe i can just leave this way? But i'm afraid that floating inputs will pick up a lot of noise.