switching power supply with symmetrical output

Good morning to all Forum

I'm new to the forum and would like to help at all if possible, some members have projects with electric scheme on power switch, I need a design of a switching power supply with the following specs, will have automatic entry to TENCE range with approximately 90 to 250 and symmetrical output of +26 and - 26v DC at 6 amps and + / - 300 Watts, this power will be used in a type class D amplifier
I appreciate everyone's attention the forum for help.

Regards to all

Carlos Leite