If, because of room setup requirements, the primary listening spot is about two feet from a wall with one of the listener's ear facing the wall (i.e. wall is next to listener rather than behind him) will SPL meter readings accurately measure the listener's subjective experience?

I'm at my wit's end here. The meter, pointed to the ceiling, reads 70db for all channels using my NAD T773's test tones, but the right channel is clearly too weak to produce a persuasive orchestral soundstage. All the instruments seem to "bunch up" from center to left side of what should be a continuous soundstage from right to left speaker!

What's going on here? Close to walls, do human ears hear things differently than Radio Shack SPL meters?

Yes. Remember that an ideal SPL meter (which the RS is not but aspires to) measures all the frequencies equally and almost equally from all directions (especially when aimed at the ceiling). OTOH, the human ear does not have equal sensitivity to all frequencies (highest senstivity is in the 3-4KHz range with reduced sensitivity above and below) nor is it omnidirectional (the shape of the pinna and head take care of that and it accounts, in part, for our ability to localize sounds. Look up Head Related Transfer Function or HRTF). So, bottom line, you will need to adjust your settings carefully to account for this.

I suggest the following procedure, if you can: Get a signal that you can send to pairs of speakers (L+R) (L+C) (R+C) (SR+SL) (SR+R) (SL+L). With each pair, try to adjust the relative levels so that the central image of the pink noise is centered between the speakers being tested.

Or just adjust to taste but with care.

What I would say is adjust with pink noise so everything is equal with the SPL meter, then adjust slightly from there by ear.

I "feel" (use this word to deflect criticism ;) that the Radio Shack SPL works well in conjunction with AVIA or test tones of a narrower bandwidth.

The DVD takes into account the source especially if you listen to your cd's through your dvd player.

Receiver test tones IME have less center channel and the bass is usually off as well.

Grab AVIA from a friend or get it through Blockbuster or Netflix.

Good luck.