I heard the HIFI module cripples when it is not ran on OTG mode and thus should not sound great when paired with PC.
If interested: https://www.seeko.co.kr/zboard4/zboard.php?id=m_device&page=1&sn1=&divpage=1&sn=off&ss=on&sc=off&select_arrange=headnum&desc=asc&no=62
I'm not sure what you mean when you say "the HIFI module cripples when it is not ran on OTG mode".
OTG mode only applies to devices which can act as a host and/or a client depending on what is connected to it which the HIFI module isn't.The HIFI module is always a slave(client) like say a keyboard or memory card.
The link to the measurement just shows that different sources(host) to a DAC measures differently and in the case above,
it just shows that he has a noisy PC
. It does'nt mean that the module is noisy.
If the same measurement is done with any other DAC let say the audioquest dragonfly DAC with the LG G5 and PC as source(host) you would most likely see the same trend.
That's to say that the PC as a source is much more prone to noise issues especially when connecting a DAC directly to the USB port.
I recommend using a USB filter to connect whatever DAC your using between the PC USB port.
I'm using the Elfidelity USB power filter if you are interested(No affiliation with it).
http://www.amazon.com/Nobsound%C2%AE-Elfidelity-USB-powered-revolution-USB-audio/dp/B00WWPG1CW/ref=sr_1_1?ie=UTF8&qid=1464271861&sr=8-1&keywords=Elfidelity+USB
Below is the measurement of 5 volt noise from my PC usb without the USB filter.
With the Elfidelity USB Filter.
So I still stand in saying that the hifi module does sound good when using it with a PC as a standalone DAC. Not as good as my desktop DAC but pretty damn close
.
On another note, those that is using the HIFI module/Camplus and is always removing the module to change batteries or for some other reason and like to use a case, there's this DUO case by VOIA which can be bought from Gmarket global(yes they ship worldwide). Search for Voia G5.