Well actually I haven't any idea about it, I wasn't even aware about this difference
I've got not knowledge at all about electricity and yes I was thinking to use the stock adapter as I've read the same then you.
But I guess this should not make a difference as some people use it ( the iDefender) without external power i.e. just with the USB OTG and as you say to purchase the iPower is a nonsense economically !
On the other hand I'm definitively sure this is not a power related noise because I've tested with different wall-plugs and without any (USB only) and it doesn't make any difference, always the same hissing and statics, while if I unplug my PC USB I've no noise at all even with the M300 powered on and at the opposite if I switch it off and I plug the PC USB again there is noise ( with the amplifier on ofc ).
Also it seems to me there are a few here which use it with no noises at all so I wonder if they have it plugged to a laptop instead of a desktop like me or what other difference it could be.
Personally
I will try hard all what I can to keep it and I'm even thinking to contact SMSL to ask them if they can mod it with a separate 5v power plug and an USB 2.0 type B input like the most of DACs have. And I'm willing to pay them if needed.
The reason being I would like to use my old USB cable by QED which has got very good shielding and build quality, as in the past before purchasing the BC-acoustique EX-202.2 I was using active monitoring (Presonus Eris e5 ) and I had experienced similar hissing and radio interference too which were strongly reduced by using it.
Unfortunately I cannot use it now because it's virtually impossible to find an "USB 2 B female -> microUSB male" adapter.
grrr stupid USB standard which use
almost the same name for all of its connectors which make finding the
exact type of adapter a real pain in the @$$
I've had spent almost 3 hours Saturday night searching for it among hundreds of different answers to my query without finding any !
I would really like
@amirm or
@SMSL-Mandy could help us...