Selling gear back in 1978 or so with vinyl as the main source, Steely Dan's Aja album was perhaps generally considered one of the best and most utilized popular recorded rock/pop demo albums for demonstrating sound quality to rock music fans, though not strictly "rock" really throughout in the pure sense. Much similar with Steely Dan's GAucho album afterwards. "The Wall" an DSOM by Floyd were other standards used but more esoteric in appeal. Fleetwood Mac's self named album from the mid seventies that first featured the version of the group that became a monster seller starting with Rumours is another that comes to mind.
Another personal favorite of mine at the time was the 2 disc "The War Of The Worlds" release by Jeff Wayne. I sold more stereo systems using that as a demo than perhaps anything else! Richard Burton's voice as narrator and the orchestral scores reeled in the elders with money and "Forever Autumn" was the feature tune that sealed the deal.
Great memories playing WOTW and others on the best feature system in the house at the front of the store facing the passers by strolling in the mall, and freezing them in their tracks to listen, and often buy. SOmetimes I played things a bit too loud and pissed of some workers in the stores across the corridor. :-). I probably would not be allowed to do something like that at all these days. Things were a bit looser back then, and it paid!
A lot of good stuff has come along since, both on vinyl and digital. I could probably come up with a sizable list of Elton John tunes alone.
