For those who take schematics and design their own PCB's. What concerns should I have when placing the components. I believe that I should try to keep power away from signal, and to always pay attention to polarity. Beyond that, does placement impact the sound? Should certain parts be placed closer or farther from each other. Maybe I'm over thinking this. ::)
Power filtering capacitor for each IC should go close the the IC in question.
If there is any sort of clock, don't put it near anything audio.
I think that is about all I usually care about, other than trying to make symmetrical patterns with components on the board. ;D
This is the typical power section I use.
If it's a high-gain circuit, I try to keep low-level signal traces and leads (input) away from high-level traces and leads (output) to reduce unwanted oscillation. If I use a charge pump (converting +9V to -9V or +18V) I try to keep those and their caps far away from the audio path.