When you read reviews on assembling a great system there is always a great deal of emphasis placed on impedance matching between components. I believe this is so each component can successfully drive the next one in the chain. If it cant do that, there is a general softening of the sound quality and reduction of bass.

I am aware of a couple of facts

1. Cables etc may add a bit of impedance, but for short runs they are not a big contributor.
2. A high input impedance makes a component easier to drive than a low one. This shows itself in an obvious way where speakers of 16 ohm impedance are more easily handled than those of 4 ohm.

So my first question is "Does a fully passive volume control contribute significantly to impedance, or can it be viewed as 'invisible' ?"