Speaker placement is the biggest factor to proper or good imaging IMO. And sticking with the room and acoustics, absorption or diffusion at reflection points which was already mentioned. And equally important is keeping things clear of the speakers themselves. No TV between the speakers. No rack of equipment between the speakers. And to a lesser degree, bass trap absorption which cleans up frequency response, and as a byproduct decreases smearing of images. And also good AC power is a factor in achieving the imaging that is in the music recording. If the AC power is dirty, the noise makes it way in to the signal path resulting in smearing of image location. I believe that if you do all of the above really well, and you take a good pair of speakers and average or decent electronics, the result will be pretty darn good imaging.
And I don't look for a change in electronics like a preamp to do anything for imaging or soundstage. To me the changes are so small and pretty much irrelevant compared to what acoustic tweaking does. I'd rather a change in electronics improve other areas of playback.
I think that's pretty much what you said, James. So count me in as agreeing with you.
To me imaging is important but not as much as dynamics, frequency response or tone. Imaging is the location of where some note occurs in the recording. But it's not the note itself. Big difference.
The above factors for getting good imaging are also the keys for dynamics, frequency response etc. So if you can get the acoustics setup right and good AC then EVERYTHING, not just imaging, will fall in to place.
The problem is, a lot of people want great sound and will spend a lot of money on a stereo including speakers and electronics hoping that the more they spend on better quality equipment the better things will sound, but IMO most audiophiles have horrible speaker placement. Almost every dealer room I've heard or seen had poor speaker placement and the sound is poor to average but hardly ever stunning. Most but not all audiophiles I know don't have a dedicated room and have poor speaker placement and setup and the sound pretty much sucks. But the components themselves are top notch!
Bryan