I use AUDACITY to record from both the desktop, radio app, dvd audio, and external sources such as dvd player audio, vcr, and the like. I also use an A/V selector to switch from the desktop line out and the external source at the a/v box on two distinct ports. The box out goes back to the desktop line in and an amp/speakers at the same time via audio “ys”. The issue is which input in audacity to use for each source. Currently I have selected MME, LINE IN, SPEAKERS OUT. I have found that external sources ONLY work inputted to LINE IN as opposed to STEREO MIX. Desktop outputs will record using both LINE IN and/or MIX. Is this normal? Can I use LINE IN for both? The sound quality is the same. Simpler. The selector does the same thing. Advice please.