Transfer H1B from one employer to another employer without stamping.

i got H1b 2016 visa from one A company which was approved but not stamped.

i got one more offer from B another company where they are ready to send me from their company. is transfer possible? without stamping from A company.

i have visa reciept only with me. does it help. if so guide me accordingly.

can any one help me in this.

thanks

kiran guttula