Hey Sirclyde, I'm still experimenting a little, however the Axiom handout that came with the 500 says to put it "Midway to 9 o'clock" position for starters. That sentence is misleading, I originally took it to say that 9 o'clock is the miday position, which it is halfway of max. After talking to Tharkun and Ajax, they say your supposed to start around 4-5 o'clock which would technically be about the midway point of 9 o'clock.
Anyway, you really need to run the pink noise test and set all your speakers to 75dB's for starters using the receivers level adjustments. The first time I did this when having the sub at 9 o'clock, the receiver had to be at -10dB to achieve 75dB on the meter. I thought that was interesting as my 350 sub was more like 0dB with the volume knob at 12 o'clock.
Then I tried it again and turned the 500 volume down to about 6 o'clock and reran my pink noise test to set all speakers to 75dB. This time the sub on the receiver was more like -2dB to achieve the 75dB reading. Alan at Axiom has always said to leave the receiver setting at 0dB and adjust the volume knob on the sub until your at the appropriate reading.
Now this does not say you can't crank it up a bit higher, it is just a starting point to get all your speakers calibrated correctly, then you can go from there. Also, I always bump up my center a few notches from what the meter says to hear the voices better.
Also on the 500 you have the trim setting. Flat is for very large rooms. For medium I think the handout says to use half or cut modes, you may want to experiment. Then you have phase, this one most people can't tell any difference. Pick the setting that gives you the best and full sounding bass signals.
