Howie, I'm convinced one can divine the essence of a piece or tweak in one sitting. If you end up "uming and ahing" after several songs that signify different aspects of SQ, that piece is not for you. There are obviously caveats to that, you might love Apogees at a demo, but wouldn't put them on yr flea Watt tubes at home.
The only area where one COULD get it badly wrong is in the bass. Lots of demos appear full or thin in the low end. Even now after 22 yrs in this hobby, bass character can be v hard to give a reliable verdict on.
But AB comparison of gear w wholly different bass presentations, w music that is tonally different cut to cut will usually decide it. When I demoed IsoAcoustics Gaias v Revopods footers, the former were warmer and fuller, the latter the opposite. Gaias nearly got the nod. But 30 mins later, cut after cut showed the more accurate and indeed natural Revopods were the clear winner.
My guess is you heard something like this going Statement to Extreme.