Some of the schematics I am reading have two types of phone jacks, stereo and mono. the jacks are usually labled as Input and Output, and two out of three have the stereo jack on the input, and the mono jack on the output. I am really getting confused now, because I only have one of each for my project. the foxx diagram has the mono on the input, and the others have the stereo on the input. any good ideas on this? which way is best? most common? does it really matter?