Sony is also big enough to dictate or manufacture custom parts (e.g. ICs, etc.). You can only get so far with off-the-shelf parts and some of the "good ones" have gone out of production. That and the small market size probably account for the Astell&Kern price structure– it has been shown, over and over, that the market for high end consumer audio is outside most manufacturers' comfort zones (compare with HiFiMAN, for example, or V-Moda's Vamp Verza).
Their re-interest in portable hi-fi is a good sign.