I did include the complete model number
It's made by LG and its the V20
Must've missed or misunderstood.
Took a bit of digging (all in about 15 minutes), and we can cut through the marketing schtick:
- It has an ESS Sabre 9218 2ch DAC ("QuadDAC" is marketing nonsense, if you were wondering)
- The 9218 advertises a built-in headphone amplifier (which I'm assuming the LG uses), which touts its ability "to drive high impedance headphones." I have found absolutely nothing (in probably half a dozen reviews, the LG website, etc) that mentions anything about "needing a higher impedance load to 'engage' this feature" however.
- Very much of this device and its actual specifications are shrouded behind marketing double-speak, but some sources have tried to unravel the whole thing: http://www.androidauthority.com/lg-v20-quad-dac-explained-713587/
- It appears that ESS specifies it with "up to" 2Vrms output, which would comport with the ability to drive higher impedance (and thus higher voltage requirement) loads. However they don't specify anything useful like current, or more practical like power output, but again, I've seen nothing, anywhere, that says "it must use high impedance loads to activate" or anything of the sort.
- There is a HUGE V20 thread that I turned up: http://www.head-fi.org/t/816024/lg-v20-sound-quality It does mention the prior version, the V10, at launch trying to automatically "read" the headphones' load, but that post-update this has been removed because the feature is somewhat inaccurate/misapplied (e.g. high impedance != high quality, it just means high impedance). A reddit thread seems to indicate this carries over for the V20, and that the user should be able to select "hifi mode" - https://www.reddit.com/r/headphones/comments/58yr2w/headphone_test_with_the_new_lg_v20_in_hifi_mode/
- The device tries to engage a higher voltage output mode (high gain) for high impedance loads, which is unnecessary for low impedance loads. More here: https://forum.xda-developers.com/v20/help/impedance-device-dac-t3494760 Basically what the device is trying to do is be too smart for its own good, by automatically detecting if it needs to be in high or low gain mode based on whats plugged in. Too many assumptions are made for that feature to work though, like MindsMirror pointed out - sensitivity is a big part of this discussion too, and the phone cannot "poll" that.
Ultimately this is kind of what I had projected: stupid marketing features run amok, leading to significant confusion and a device that's obnoxious to live with. There's a lot of really atrocious "reviews" or "articles" about this that erroneously claim that "high impedance" somehow equates to "studio headphones" or some other faff. Just ignore it all - its wrong and exists within its own little walled garden of reality distortion. For the absolute last time: impedance is NOT A METRIC OF SOUND QUALITY, IS NOT A METRIC OF "hard to drive-ness," AND IS NOT A METRIC OF PERFORMANCE.
Get whatever headphones you actually want/like and get on with life. The V20 should be competent to drive many things out there, at least by phone/tablet standards, and that's that.