I wasn't able to get this my DACport slim to work on iPhone 6S even with moedawg's solution of Apple CCK, m2m USB cable, >3 USB Hub and External Battery Pack / outlet power. Phone says that the accessory uses too much power. Otherwise, works amazingly on Windows 8 desktop with my 598HD.
If anyone has gotten it to work on iPhone 6S, please share.
If anyone has gotten it to work on iPhone 6S, please share.