Gustaty: Whoever is giving you advice regarding your amp being too powerful for use with your speakers, since they are "too efficient" is more confused than you are. As such, i would avoid asking them any further questions as they are only going to make things worse.
Judging from what you are telling us, it sounds as if something is wrong with the amp. You shouldn't have metal "clanging" sounds coming from within your amp under any conditions. I can't think of anything that would cause this to happen short of a noisy fan kicking off or on.
As far as having to really crank up the gain on the preamp, Kef's are typically not real efficient. With a decent level of drive from a typical line level source ( tuner, CD player, tape deck, etc... ), you should pretty much have a very reasonable listening level by the time that you hit 11 o'clock on the volume control. If your sources are slightly weak on output or you have a quiet recording, you might have to adjust the gain setting on the preamp up to about 12 o'clock or maybe even 1 o'clock on rare occasions. If you have to turn it up this high or higher all the time, something is wrong. Judging from what you've said here, my guess would be that your amp is going goofy. Hope this helps... Sean
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