Sony STR-DA5300ES - how to get 5.1 Channels with Linear PCM out of a PS3

Just a quick one to help anyone that might be having the same problems I've been having. I have a PS3 running over HDMI into a Sony STR-DA5300ES amplifier. I had the PS3 set to output Linear PCM rather than bitstream (because the PS3 doesn't support bitstreaming Dolby TrueHD). That's fine. I'm leaving the decoding to the PS3 by using Linear PCM, so theoretically when I set the amplifier to AFD Auto, it should just allow the 5.1 channels (that's all I've got) to receive the signal. Up until an hour ago, all I was getting on the AFD auto setting was 2.1 channels - no blue light on the front of the amp. I checked everything - I thought. The display on the amp read Linear PCM, so that was correct, the sound field was on AFD Auto, so why was I only getting 2.1 channels?? Finally, the penny dropped. I'd forgotten the hidden setting: You have to go into the PS3 settings menu - 'Sound Settings' - 'Audio Output Settings'. Select HDMI, then continue and allow it to select every possible option for HDMI, all the Linear PCM modes. Then hit the X button to save. Finally, the PS3 will be outputting the highest available format to the a/v receiver. You'll get the blue light coming on (as the amp decodes the LPCM signal) and 5.1 (or 7.1 or 9.1, depending on your system) going to the speakers. Hooray! I certainly didn't want to use one of the other modes, like AFD-Neural THX, which takes a stereo signal and tries to make it sound like surround. At last I can relax and listen to Ironman the way it was meant to sound...
It took me a couple of hours of Googling to find the answer. I hope this helps someone who has the same problem.