I have a portable amplifier fiioe12a.
The v10 / 20 does not need! HighGain trick is beautiful and strong voice.
But the galaxy S7 MUST because of poor amp. (By the way her voice quality is very far from v20 to.) These sabre DAc / AMP that are in the V series, the phone is exceptional. In my opinion there is no better. ( in phone category )I emphasize, HighGain trick + poveramp v3 (Either HTC or samsung or any other, there's no better ZTE axon 7 too)
(I tried the Fioo e12a in the V series, redundant, not have been better, the AMP's own right!)
With these two, inexpensive device used in the V10 and V20 to use it at. (High Gain trick) so all kinds of root - without viper4a) is worth a try. :
http://www.ebay.com/itm/DUNU-3-5mm-to-3-5mm-Impedance-Adapter-Plug-For-Hi-Fi-player-AMP-DAC-Earphone-/380932180092?var=&hash=item58b153c87cmTYTIMVVhRj3Y73N82lrXLg
http://www.ebay.com/itm/New-L-Shape-Right-Angle-3-5mm-Male-To-Female-Stereo-Plug-Adapter-Connector-HFUS-/390645010934?hash=item5af441d1f6:g:AyQAAOxy-NVSDu1a
The high gain, the following tips: (Because it may be that not everyone is familiar with the method, when to me, then I'm sorry to be so repetitive.)
Let's buy an extender (such as this or functional ear headset / headphones have a 75 ohm impedance and interface.
1, Connect the Extender impedance adapter, and then this "ensemble" plug in the phone's 3.5 mm jack socket. At this moment, the V10 high gain mode.
2, If you pull out the impedance adapter (and only remains plugged into the Extender) in the V10 remains high gain mode.
3,then plug the headphones were plugged into the Extender is on the phone (Small aesthetic problem is that the Extender is plugged in while listening to music.)
The above method, of course, the headphones just under 50 ohms should be used.