which classenti do you recomend for my 4 year old son. he has just started lessons

That "Classenti" DP has a 5 year warranty, but the spec. isn't brilliant, only 8 voices. However as most of us want a DP with a good grand piano sound and a realistic touch perhaps 8 voices is enough. You have to try them out, I wouldn't buy a piano I hadn't tried first.