The synthesizer dance Adagio for Strings you were referring to; Eric Carmen turned one of the major strains of the Rachmaninoff into his cheesy power ballad, and the long "album" version even has a considerable stretch of the original piece in it.Did what exactly in reference to my post?
As noted, popular groups taking classical pieces has a long long history. Way way back in the days of vaudeville and even traveling minstrel shows, "light classics" performed as piano or reed organ reductions were a common part of those shows. Out in the hinterlands, before the phonograph, the only way to hear any classical music was to buy a sheet music piano or organ reduction and play it yourself, or to hear a traveling troupe perform it.