No HD audio with STR-DA2400ES

[Patient-X]

I have a problem with my STR-DA2400ES.

I have a BDP-350 connected via the BD HDMI input. The player is set to 'DIRECT'. The problem I have is more often than not I'm not getting HD audio (DTS Master or True HD). All other audio (DD, DTS etc) is fine.

I'm certain it's not a problem with my player, I've tried another 350 through it aswell as a PS3 and a Panasonic BD-55 and the problem is the same.

Sometimes I can turn the receiver on and it's fine, the next day I can turn it on and the HD audio has gone again. Sometimes turning the amp off and on solves the problem. Sometimes just going into the GUI (not changing any settings) and coming out of the GUI will solve it. Even skipping a chapter sometimes works.

I've taken it in for repair at an authorised SONY specialist, but they said they found nothing wrong with it (although I did have trouble making them understand the difference between the HD audio and Digital audio.

Maybe there's something I'm missing in the set up menus, but the fact that it does sometimes work makes me believe I have it set up fine.

Has anyone had a similar experience or any idea what the problem might be?

Thanks