It is possible to do that by doing the following steps :

1. Open "..\GStudio7\data\option.scr" with notepad
2. Locate to the line :
; save the WMP file in the binary A7 format
SAVE_WMPB = on

3. Change SAVE_WMPB = on to off
4. Save and exit

5. Create and save a new level in A7
6. Open it again in A6 WED
7. Done