Phil, you've hit on a topic that is near and dear to me. I've been a huge fan of the 78 rpm format since childhood. No longer willing to move the collection--a Herculean task--I recorded my favorites onto reel-to-reel tape and divested it over a period of time to the then recently established Archive of Contemporary Music (a suggestion made by my college roommate who had relocated to NYC), a historical society, a collector, and (shudder) the local landfill.
While the reel-to-reel tapes were lost/damaged/accidentally recorded-over in the shuffle of various moves, I've found many of my favorites on CD (eBay/Amazon) and iTunes.
Hearing Mabel Scott belt out 'Mr. Fine' without the surface noise of a 78 was an ear-opening experience. Some of those digitally restored oldies sound fantastic without the extraneous noise inherent in the 78 format. Ditto recordings by Ruth Brown, Perry Como, Bull Moose Jackson, LaVern Baker, Bing Crosby, the Nat King Cole Trio, Kay Starr, Helen Forrest, Paul Weston & His Orchestra, Harry James, Dick Haymes/Orchestra, Dinah Washington, Frank Sinatra, Jo Stafford, Ruth Brown, The McGuire Sisters, Eileen Barton, Stick McGhee, and many others.
One of my favorite classical pieces is Rachmaninoff's Symphony #2 in e minor. I have at least a half-dozen recordings of it, but my hands-down favorite is a 1947 recording by the Minneapolis Symphony Orchestra (now the Minnesota Orchestra) under Dimitri Mitropoulos. I listened to that for years on 78s. A lengthy search (years, actually) produced a digitally-preserved (but, unfortunately, not remastered) CD of the recording on a Russian label. It's one of my desert-island recordings.
Thanks for the great photo of a four-armed turntable! How they're used: Each tonearm is equipped with a different cartridge/stylus to determine which one sounds best with a particular recording. This is done by quickly switching between the signal of each tonearm and comparing the sonic characteristics of each stylus.
It's generally used in studios that specialize in preserving 78s to digital formats. The one shown in Phil's post has tonearms long enough to play 16" master discs (78 rpm format).