The original SACD player.
If the format has yet to become market-wise successful, Sony's SCD-1 became very quickly -and remained so- the reference SACD player for a good many years.
Price-wise a little too expensive for many, so the similar SCD-777ES made most of the sales for Sony. The SCD-1 was however much more successful than the 1992 CDP-R10 and DAS-R10.
Given what is left of the high-fidelity market, SACD might remain a niche until the next (un-necessary ?) (r)evolution. But with the overwhelming craze over anything downloadable and conveniently compressed (quantity vs quality), I sincerely doubt SACD will remain a "niche" market as long as LP replay has since its demise as worldwide standard for the masses.
Because SACD so far didn't become a worldwide format for the masses, and didn't have the time to either.
I for one believe SACD to be the last worthwhile audio format : a great step forward which would've needed to be launched only a couple of years earlier - before mp3 landed on the scene and forced manufacturers to adopt a deadly dual-language :
SACD is great but expensive,
mp3 is great and free.
It was easy to spot the winner even before the race started.
After the "1" lineup (SCD-1, TA-E1, TA-N1 and SS-M9ED), Sony gradually shelved all 2-channel high-end audio development, thus becoming the last of the japanese majors to exit that ever-diminishing market.
Production was planned at 500 units /month for the SCD-1 and 700 units /month for the SCD-777ES sibling.
There were at least 2500 made in total, the last batch bearing the post-2000 Sony EMCS T-tag sticker pasted over the original Sony Kitakanto.
You can see three SCD-1 prototypes in the Invisibilia section of TVK.