gonk,

Thanks for clearing up my confusion.

6.1 is NOT the same as turning on the centre rear speaker. Processing 6.1 is enabled be pressing the Surround 6.1 button on the front panel. This as nothing to do with the Dolby EX thing. The workaround is to leave Surround 6.1 alone and just go into Speaker Config... scroll through until you come to the centre rear speaker and set it to ON.