Hi folks. This is my first post so make allowances please I'm resurrecting a system that's been sitting doing nothing for the past 20 years. The amp is a Cambridge A60 and the speakers are Rogers Compact Monitors. I was quite surprised that it actually worked when I plugged it in but it's all OK from the fact that the controls on the A60 are noisy. If I alter the volume/balance/treble/bass knobs I get crackles and hiss while they're turning. Is there any fix for this please? Will they just sort themselves out with a bit of use? I'd rather not open the amp up if possible. Thanks.