What's the consensus of opinion on their efficacy or otherwise?
Due to a suggestion from a friend I decided to revisit the old ferrite clamp thing (which I hadn't experimented with in years) and attached ones to various cables throughout my system, both signal and power-carrying, with pretty good results. Due to past experiences I had been very sceptical beforehand whether they would work or not.
There is a noticeable reduction in background noise and 'hash', creating a 'blacker silence' from which the music to emerge. It's interesting as I didn't like their effect in a Naim system some years ago but in my current valve-based set-up the effect is positive resulting in a marked improvement in sound quality. I currently do not use any other filters on cables in my system, passively, or actively at source via a mains filter (although this will change shortly with the addition of dual TD mains filters for both the analogue and digital sections of my system), although I do have a separate mains spur.
Any theories as to why they're effective now but weren't before? Also, what exactly are ferrite clamps designed to do in a technical sense?
Cheers!
Marco.