Make sure your connections are rock solid. I have those awful plastic shrouded speaker connectors on my Marantz and it was always difficult to tighten them down. As the connectors tighten, the plastic shroud and the metal contact seem to move as one but I've always wondered if the plastic tightened first before the metal. I've even read where some people have broken off the plastic since the spades can only be inserted one way and one way only, adding to the problem.
Anyway, I went and had the amp end of the speaker cable swapped out from spade to banana and all I can say is what a difference it made. The connection is so much better that it's the old "I'm hearing things I haven't heard before" reaction to very familiar CDs. All of this from better connections. And yes, I cleaned the spade connectors a few months ago so it's not that they were dirty. :-)
All the best,
Nonoise
