People (not you) should REALLY stop obsessing over the high impedance mode, this is getting ridiculous.
You DO get the Quad-dac engaged even with normal impedance IEMs/headphones.
Many people including me have said it a number of times: high impedance mode DOESN'T sound better with IEMs that don't need high juice and higher volume.
Of course it's annoying not to be able to choose impedance modes, but I really wonder how anyone could prefer a X5iii to V20...
X5iii UI is a complicated mess, and the autonomy is downright horrrible. And I can't even say I heard anything better with the balanced output, unlike the additional power and slight enhanced soundstage that can be appreciated with some other DAPs (not all). It's like X5iii was beta-testing ground for the X7ii (= much better experience).