I wouldn't follow the advice regarding yanking out ceramic power supply
bypass capacitors and replacing them with polyester. Ceramic capacitors
have a low self (series) inductance and are chosen for that purpose. No
audio is in series with those bypass caps anyway.

This is a good write up on ESR/self inductance and how to measure it.
http://www.emcesd.com/tt020100.htm

Otherwise, the none of the suggestions on the Kiwa page will do any
harm and may do some good. Polystyrene caps are really about as good as
it gets, but they are huge. I use them in situations where leakage has
to be low.

To be honest, the Kiwa article is a bit dated. I'd suggest going for
Sanyo oscons on the power supply rails