I need to fix a light weight hi-fi (2kg) to a wall. On inspection the wall
is either lathe & plaster or plasterboard - hard to tell, but I suspect the
former. The tiny hole I looked through showed no sign of any timber, but
judging by the age of the house/wall I suspect that is could be just a small
gap between them. Problem is that the plaster is very think - I would
estimate around 2cm at least.

As mentioned above - the hi-fi is very light, will not be manipulated much,
and only sticks around 15cm from the wall.

Any thoughts?

TIA.