Most U.S. radio stations were still AM one's in the mid 1970s. And these AM-stations broadcasted their music in mono at the time. And let us not forget, that there were millions of radio listeners at home or in their cars, still using equipment that could only receive programming in mono. Featuring cuts like “Baby Love”, “You Can’t Hurry Love”, and “Where Did Our Love Go” from her time with The Supremes and solo hits including “Ain’t No Mountain High Enough”, The Greatest is a journey through a six-decade spanning career.

However, with the increasing popularity of FM stereo radio stations in the mid 1970s, new FM-receivers were developed, allowing mono as well as stereo signal compatibility. Furthermore, the reason why the Motown record company had to include the mono versions here was a "technical" one:The ensuing years have been marked by the sense that Diana Ross doesn’t really know what to do to rectify the situation, or perhaps isn’t that bothered either way. A disastrous attempt to reunite the Supremes in 2000 aside, her tours still rake it in. In the studio, a nadir was reached with 2006’s I Love You, a covers album Ross audibly approached with all the enthusiasm of a hostage reading out their kidnapper’s demands. You could see why. The album appeared to have been masterminded by someone with a longstanding grudge against her: how else to explain the cruise-ship cabaret takes on The Look of Love and Take My Breath Away that lay within, not to mention the big band take on Queen’s Crazy Little Thing Called Love, complete with widdly-woo guitar solo by Brian May? But not, as it turned out, for Diana Ross, whose recording career stalled shortly afterwards. She had her last US Top 10 hit, a tribute to the recently murdered Marvin Gaye called Missing You, 37 years ago. Britain remained under her sway a little longer – Chain Reaction, a flop in the US, rightly reached No 1 in 1986 – but even so, it was all over bar the shouting by the early 90s.

This rare, promo-only issue is a 100 % legitimate release similar to so many other pressings made available to U.S. radio stations only throughout the 1970-1980s. Another, prime example on how other record companies served radio stations during this era was Elektra Records. This label comprises a vast catalogue of such promotional 12" stereo/mono pressings for radio play. Selected items are only available for delivery via the Royal Mail 48® service and other items are available for delivery using this service for a charge.Diana Ross is releasing her greatest hits compilation, The Greatest, on limited clear vinyl this December.

Or to be more technical: Since mono AM-receivers use the L+R signal only, the newer equipment at the time could decode both, i.e. L+R and L-R signals. Therefore, these more advanced systems were able to reconstruct the original L and R mono signals as well, making listing in mono and/or stereo possible - no mater whether you tuned into an AM or a FM radio station.