Told you man
Since 2015 MBP n iMac, Apple has included a great DAC in its lineup and 2016 could be even better.
Thanks for confirming this as I just have HD598Cs for now, do try to run HE400i on them
I also use Boom2 which further enhances the sound
And I hope u already know that ur audio jack is also SPDIF out also n u can plug an optical line to ur DAC through that
About the battery well, this just shows u how bad is windows with battery/power management. How much time ur getting with ur mac osx?