The noise when turning the master volume control whilst playing is still there but doesn't affect the sound otherwise. May be a 'design faultfeature'.
One thing I have noticed is that I have to use the -15db setting (never use the pad on my other amps) as without it even with the gain low it clips very easily and sounds compressed/squashed (compressor off), is this the 'Dynamizer Technology'?
Overall I am happy with the amp and will be keeping it. It is now my mini rig, paired with a recently purchased TC RS212.