Thank you for the speedy feedback.
The deepfreeze is positioned away from pipes and cabinets. I think one issue is that the property was converted in the 1970's and the sound proofing between floors is pretty poor, hence my thinking about some form of buffer the freezer could sit on.
My tenant has complained that the noise/vibration from the fridge/freezer in the flat above his is keeping him awake at night. The occupier above has tried putting pieces of carpet under the feet of the fridge/freezer, which stands on a wooden floor, and whilst this has helped it is still too...