Hi there,
This is a bit off topic but hopefully relevant to the SID noise discussion! I have been looking into a few simple mixer circuits on the web
(http://www.musicfromouterspace.com/analogsynth/stereoinputmixer.html)
and trying to get my head around the theory of operation in regards to people recommending tanatulum capacitors (see the previous SID noise discussion). I was wondering if the choice of capacitor size changes the audio quality? The reason I ask is that there is 1000 percent price difference between 0.1uF and 47uF tanatlum caps 
Looking forward to someone more knowledgeable to reply!
regards
Dave mK