Hi Steve
I don't think the problem is feedback vibration from the speaker. I have
listen even in headphones and then the speaker is quite.It is when I turn
the tuning knob I can hear a rassle sound even in the headphones.
/Lars
skrev i meddelandet
ups.com...
It shouldn't happen so long as you're listening at normal volume
levels, though the user's manual does state that you can expect some
vibration to occur if you turn the volume up high.

The solution is to get a decent external speaker. You ought to use an
external speaker anyway. Only an external speaker will do justice to
the high quality audio produced by the 150.

Steve