As this seems to be the most asked about/problematic area in the setup of HD sources I thought I would write a little explanation and guide to setting up these items to get the full experience. If the mods wanted to make this a sticky or anyone has things to add or correct, please feel free. The following is assuming a PS3 and a 605 amp. It is relevant to the higher end amps but the menu options may be different. I can only speak for the hardware I have. OK here goes..... First a bit of background knowledge on the connections and audio formats: Optical connector (sometimes called TOSLINK) This connection has limited bandwidth and can only supply Dolby Digital (Bitstream) DTS (Bitstream) PCM (2 channel stereo) HDMI connector (in brackets is the minimum revision of HDMI needed for that format) Dolby Digital (Bitstream 1.1) DTS (Bitstream 1.1) Dolby Digital plus (Bitstream 1.3) Dolby TrueHD (Bitstream 1.3) DTS HD (Bitstream 1.3) PCM Multichannel (1.1) Ok, from the above list you can see that HDMI can do a lot more than optical. So, surely this is the best way to go, correct? A little bit about PCM (and LPCM) and bitstream. PCM stands for (Linear) Pulse code modulation. This is an uncompressed stream of audio. As it is uncompressed, a lot of information is sent along your interconnect cables. This is why the limited bandwidth of an optical connection only allows a stereo PCM signal to be carried. Bitstream is a compressed signal (sometime lossless, sometimes lossy). This is why a bitstream 5.1 signal can be sent over optical. Because it is compressed, effectively more information can be sent. However, even compressed, optical cannot handle the new HD formats as they still exceed the optical connections limits. Now, for bitstream to end up coming out of your speakers it has to be de-compressed. This can happen in your player or in your amp. The difference? Well, if you decode in the amp it will tell you which format it is decoding and outputting. If it is decoded by your player, the amp is only getting uncompressed sound, it does not know what compression method was used (DolbyTrueHD, DTS HD etc). This is why, when you decode the audio in a player the amp will only show 'Multich' and the pretty lights on the amp will not light up. Ok, got that, so what should I use on my PS3? Well, here is the issue. HDMI is the best (looking at the above comparison) for carrying the sound. So, you only need the PS3's HDMI cable connected to your amp. However, there is an issue with the 'fat' PS3 and bitstream. It cannot send any HD audio format bitstream via HDMI - it just doesn't do it. Some say it is due to a custom HDMI design in the PS3 that doesn't allow it, some say Sony just haven't bothered and it can be updated in firmware. Who knows? All we know is, it doesn't at the moment so that option is out. And optical is out as that by design cannot. The new 'slim' PS3 CAN now bitstream HD audio (the 'fat' PS3 still cannot). Now, the PS3 can decode all of the audio formats (standard and HD) and send via PCM. Right, so what do I need to set the PS3 and Onkyo to for the 'best' solution? So, from above we can deduce that HDMI and PCM (in the case of the fat PS3) is the best option. To do this do the following: Turn on the amp and select the source that your PS3 is connected to (DVD, Gam/TV etc) Turn on your PS3 On the fat PS3:- Select Sound Settings Select HDMI Select AUTO Check that all the DD, DTS and a number of PCM (all the way up to 7.1) are ticked. Save the settings Go to the BD/DVD settings Select audio output format as PCM and save the settings. On the slim PS3:- Select Sound Settings Select HDMI Select AUTO Check that all the DD, DTS and a number of PCM (all the way up to 7.1) are ticked. Save the settings Go to the BD/DVD settings Select audio output format as bitstream and save the settings. On the Onkyo: Press Setup Select Input/Output Assign -> HDMI Input Go to the line for the source that you want the PS3 to appear on and set it to the HDMI socket that you plugged the PS3's HDMI cable into (IN1 or IN2). Press return Select Digital Input Check that the input you assigned your HDMI to (above) states 'HDMI' Press setup All done! OK, done that but what if I want the amp to decode where the PS3 can send bitstream It seems some people would like the amp to decode when the PS3 can send bitstream (only on DD and DTS soundtracks on the fat PS3). To do this: Bring up the 'media player' settings whilst playing a disc; Press the triangle button on the controller or whatever button it is on your particular remote control for the PS3. Move to the line one up from the bottom and the icon that is a square with 2 lines with circles on them (titled 'AV Settings'), press 'X' Move to the bottom option (saying PCM). press 'X' move up and down to select between bitstream and PCM. Press 'X' if you get a message telling you that some audio will not be played correctly on bitstream, press 'X' to clear the message Press 'O' twice. Note that on the fat PS3 bitstream should only be selected when playing standard DVDs or BD discs with only standard Dolby Digital or DTS tracks. If you want to play DolbyTrueHD or Dolby Digital Plus you must select PCM in the above settings to get the full benefit of these HD audio tracks. The slim PS3 can send all formats bitstream so leave the bitstram setting on all of the time - no need to change! Just a point to note: As explained above, because the PS3 is decoding the audio if set to PCM, you will only see 'Multich' on the display of the amp. This is because the amp does not know what the original format of the audio was, it just sees the channels it is receiving. However, you are getting the best sound possible from the PS3 according to the audio track you select on the disc that you are playing. There is one point to mention on the 605: There is a setting to allow the 605 to send your sound to the TV. This can be set to ON or OFF. I recommend that you leave it to OFF when you are listening to the soundtrack through your speakers. This is because, when set to ON, the amp will downmix that lovely 5.1 or 7.1 audio to stereo (as it thinks your TV can only output stereo). Onkyo confirmed to me that this is the case (this is verbatim so excuse the grammar): To toggle this setting: Press setup Hardware Setup -> HDMI -> HDMI Audio Out 'ON' sends audio to the TV, 'OFF' sends no audio to the TV.