I received a replacement because the first one had a failure. Thomann has the best service , they responded immediately and they exchanged it with a new one without any extra cost.
Well the preamp is a jem for the cost of the buying. Really a big surprise, unbelievable frequency balance ...it can compare with far more expensive preamps and put them down!!!!
Finally i am very satisfied from the product and the response of Thomann to this issue!!!