Chinese manufacturer vivo has added a pair of new devices to its lineup today. The new handsets come as direct descendants to vivo X6 and X6 Plus and are all but identical on the outside. This is just as well, since the metal shell still looks elegant in silver, gold or pink and reusing the chassis should save some R&D budget, which could be better spent elsewhere. The devices both come with an even better audio hardware than their predecessors. The smaller X6S is equipped with an AKM4375 32-bit DAC, while the bigger X6S Plus has a ES9028 DAC within a YAMAHA YSS-205X audio...
Source: http://www.gsmarena.com/upgraded_vivo_x6s_and_x6s_plus_are_now_official-news-17549.php