Electrolytic Signal caps

[lowell]

which direction do they go in? My thoughts are the + is the input and - the output? IS that right?

[pdf64]

They need polarising, so + goes the the node with the higher dc level, doesn't matter whether it's in or out (electrons aren't fussy).
There will always be leakage current, so take that into consideration.
If the dc level is the same either side, special non-polarised electrolytics should be used, as I understand it.