I was recapping my Roland SMX-880 a while back and got hung up on the fact that I hadn't observed the fact that the 10uf electrolytic at input jack was a bipolar. Quick test confirmed that this cap is situated in line with the signal, it is the first thing the signal hits.

I wasn't about to put some polarized cap there, so the unit was set aside to await a parts order. In the meantime I read a bit of opinion on the internet I found agreeable: "The best sounding capacitor is a piece of wire".

Brilliant. Upper right corner, I hadn't any plans to subject it to DC anyway.