I wonder how much flavour is lost in the head?I understand that the head has an unpleasant odour so i dont think any good flavours are lost. The weak portion at the end - tail - is also discarded. The middle - heart - fraction is richest in aromas and flavours and used for the maturation process described by @chiralSPO .
For the finest brandies the distillation uses either fine wine or fruit wines - eg plum or peach wines. Cheaper brandies use blended nondescript wines which have fewer distinctive flavours.