Recapping essentially means replacing all the electrolytic capacitors with new ones. This should be thought of as a service item, much like changing the oil in your car, although with a 20 year interval rather then the one year (or six months if you’re like me). Oil is a good analogy because not only will you see a reduction in performance, but the longer you leave it, the more you risk damaging other more expensive components. Good capacitors only allow alternating current to pass through them, while blocking direct current (audio signals are ac). Electrolytic capacitors, so called because they consist of a liquid electrolyte, dry out over time and begin to leak, not physically (although this can happen), but electrically, in other words they start to allow dc through to places it shouldn’t be.

We strongly recommend ELNA SILMIC II caps, they are designed specifically for audio and have come top in various listening tests. I have installed these in my own equipment, and customers, simply as an upgrade.