At the time Sharp was known in the US (and still is) as a maker of microwave ovens, and other small appliances you'd find in a big box store. Earlier, in the '70s or so, they had a mid-level range of hi-fi gear, marketed under the Optonica name. I don't think there was much of anything to distinguish Optonica from any of the other more well-known Japanese makers. It was just 'there' on the dealer's shelf, taking space, and if it sold before Pioneer, Sansui, Marantz, et al it was no doubt because of a heady discount.
The idea of a digital ready Class D integrated amp that looked like something George Jetson might own, especially one selling for fifteen large, was something few consumers could relate to. It was simply one of those occasional 'scratch your head' sort of things you sometimes come across in life.