I've got a Marshall Valvestate (VS265), double speaker 65-watt hybrid-valve. I, for one, do actually like the sound I'm getting out of it, even though it needs a couple of pedals for good distortion.

My problem is, it's buzzing. It doesn't matter whether you have the volume turned all the way down, or which channel you are playing on. The buzz is always on the same level, except for when you turn the treble up, which increases it. This buzz is not only coming trough the speakers, but also trough the headphone jack, making it impossible to record via a line in.

I've got a few theories to what could have caused this:

Breakdown; this amp was discontinued ten years ago. It had already been trough years of usage when I bought it second hand. It sounds great, but have quite a few dents and such.

No ground; I live in Europe, but the amp is made for usage in the US. So I've got quite a chain of adapters and wires to make it work. One of those is not grounded (ground-"plug" sawed off). But I did have this problem in America too, so I find it quite unlikely.

Radio-waves; I could very well just be that it's handling other radio signals very badly. But this has never been an issue to any of my other amps.

So now I'm looking here for advice. What do you guys think can have caused this? And if you think its about to break down, please suggest what parts should be the first to become replaced.