Here is the answer to that burning question written by Matthew Polk.
This is a surprisingly difficult question to answer mainly because there is no simple answer. We began selling the SDA products in 1982 and stopped making them around 1990 except for a brief revival with the SRT system made in 1995 and 1996. From the first SDA-1 shown at CES in June 1982 customers loved them. However, this was not necessarily true of the retailers. SDA was a radical departure from the traditional audiophile concept of how audio should be reproduced and many of the salespeople in stores at that time were audiophiles. As a result, many of them hated SDA and steered customers away from them. In addition, because of the way SDA speakers work many retailers did not get them set up properly for demonstration which didn't help either. In spite of this SDA products sold amazingly well particularly when you consider how expensive they were relative to most everything else on the market. As I recall the original SDA-1 started out at $1,600 per pair retail at a time when most stores had nothing over $1,000 per pair. But, anyone who actually got to hear them was absolutely blown away and we were able to get a few good reviews particularly from Michael Riggs at High-Fidelity who described SDA as "Mind-boggling, astounding!". By 1986 we had a full line of SDA products from the SDA CRS+ at under $1,000 to the SRS-1.2 at $3,500.
But, the industry was changing rapidly. First, the era of big speakers was coming to an end and non-hobbyist customers were starting to prefer the then new sub-sat systems and the then brand-new concept of in-wall speakers. SDA speakers were big. The classic side-by-side driver arrangement meant a wide front baffle for any SDA product just as the trend was going to narrow towers and smaller speakers in general. Second, the small independent retailers were gradually turning into large regional chains with huge open format stores and non-hobbyist salespeople. The result of this was that retailers began to lose the ability to really demonstrate the performance of audio products. It's really impossible to describe the experience of SDA to someone. It really has to be demonstrated. So, as the stores became less and less able to demonstrate high performance products customers didn't have an opportunity to experience what SDA could deliver. Third, the development of digital electronics and surround sound drove the cost of high quality audio components rapidly upward but drove the cost of low quality surround sound receivers rapidly downward with a commensurate reduction in performance. Because of the channel cross coupling in SDA it is always a difficult load for an amp to drive. Many of the new multi-channel receivers just couldn't do it. So, with fewer and more expensive high performance amps the options for good SDA electronics became very slim.
So, a combination of changes in what non-hobbyist customers wanted and what the retailers were capable of selling plus changing technology made the SDA products much more difficult to sell. Of course it had nothing to do with the performance of the SDA systems which continues astonish people even today.