Hey Jeff if you figure it out let me know as I’ve had my Onkyo for 4 months and I’m still trying to decide what I like best. For now I’ve just got everything set to “Last Valid” so I don’t have to keep switching things back if I jump from one input to another.
I can tell you what I’ve found so far but I hate to say it only you can decide what modes sound best to you.
I mostly use “Direct” for both HD formats. I use “Direct” or one of the THX settings for most music because I don’t like the high frequency roll-off of the Audyssey curve which can only be deselected by choosing “Pure Audio,” “Direct” or one of the THX modes (which actually uses the Audyssey calculated “Flat” curve so no high frequency roll off unless you then select THXs RE-EQ).
For Xbox games it’s a mixed bag. Some games like “Elder Scrolls Oblivion” don’t play well with PLIIx so I use “Direct.” OTOH, “Mass Effect 2” works fine with it so I’m actually using PLIIz.
For TV and some DVDs of TV shows I actually find that “All Channel Stereo” sounds best since there is little or little out-of-phase sound for PLIIx(z) to work with.
Sadly the biggest thing I’ve found is that no one mode works best with any given input. It really depends on the material being played from that input. Best I can suggest is just to keep experimenting to find you what you like best for each situation. Otherwise just pick something that seems to sound good, map it to an input and be done with it. A safe bet would be to use “Direct” on high quality sources like HD Blu-ray tracks and SACDs and PLIIx(z) on everything else picking between non-THX and THX modes depending on if you like the Audyssey high frequency roll-off or not.
I haven’t really played around with any of the special modes like “orchestra” or “unplugged” so I can’t even comment on them.
