Capacitor for in the feedback.

These polymer-type caps have very low DF and a high series resonant frequency--I think they might work very well in some audio applications. Things to consider:

1) I believe these are all polar, so watch out if your AC component is large compared to your bias

2) I have not seen DA ratings which could cause problems

Mouser carries Cornell Dubilier ESRD and ESRE caps; compare the specs, but I think they are cheaper than the Panasonic. Might be interesting to do some tests. A white paper is available on CD's site.

http://www.cornell-dubilier.com/spa2.pdf

I will be using some ESRD caps for bypassing in my DAC.