I've had this Pio SC-1522 AVR for 10 days now, and I've found an especially nice combination of adjustments which give a good soundstage. I thought it would be worthwhile to report. First, on "soundstage", I found this on the diyAudio forum:
Soundstage is how accurately the images are placed in space. Do vocals come from the center? Do violins come from the proper location? Does whatever come from wherever it's "supposed" to? That's soundstage.soundstage definition from Jim85IROC
I'd like to have the soundstage work for all the listening modes the receiver does, but so far, I'm getting the best results with the AVR set to "wide surround movie" (using the "standard" button) and "optimum surround" (using the "auto/alc/direct" button). This uses the front wide speakers, in addition to the ordinary 7. (Since I never heard of these two settings before on other AVRs, I'm guessing they are inventions of the Pioneer engineers.)
In calibrating, I've gone through the ordinary first steps using MCACC. I ran the "full auto MCACC" procedure, changed some speaker settings (I left L, R, C "large", and changed all others to "small"), and re-ran auto MCACC with "keep SP settings". I listened for a day or so before each of these steps, and I didn't hear the soundstage come to life until after the second run through of auto MCACC.
The SC-1522 is a 9.2 receiver, and I have it hooked up to Axiom speakers. I'm not counting the front high speakers here, because they're not active in the listening mode I'm using. I won't go into the subs I connected, since I don't think they are involved with the soundstage phenomenon.
I don't understand just which of the above technical details contributes to the nice soundstage that I stumbled on, and I don't claim to have found the best settings.