For anyone who isn't an expert I came across this video yesterday and thought it worth sharing. I rather wish I'd found it 12 mths ago (Moderators - I hope it's ok to link to the video? Apologies and remove if not. It's purely instructional.)
I found it incredibly helpful & simple to grasp - once I'd got over the occasional, to-camera 'death stare' of the marketing guy. The revelation was using their recommended Norah Jones track to get my centre image. Mine turned out to be some way off to the left - I never realised. I actually had to move the left speaker closer to its sidewall to get perfect centre image. When I'd done that, a whole new world opened up. Imaging and soundstage are now the way the journo's write about them. I didn't realise what I'd been missing. Try the Norah Jones (e.g.) test and see if you're getting the most out of your soundstage..
Moderated Post: I've removed the link it as it is a manufacturers video