[Nexus 6P Q&A, Help & Troubleshooting] sewannabe:
I feel like I contributed to the pervasive pseudoscientific nonsense common in the audiophile community. That was not my intent and this post is my attempt to correct it. Sorry about the length. My statement that the low output at the headphone jack indicates that the audio system may have been inadequately considered during design and implementation was limited and specific to the general types of headphones folks use with a mobile device. My interest with my mobile device is driving high efficiency IEMs and or outputting to externally powered devices. As such I know of no recent mobile device where the output voltage and corresponding volume is limiting. If you want to drive circum/circa aural headphones directly from the 6P the opamp in your mobile device is still unlikely to stop you from finding the joy of tinnitus.

With efficient headphones (high sensitivity (dbl/mW or dbl/W) and low impedance (ohms)) most high end mobile devices will deliver adequate volume. For example: JH Audio Roxanne IEM (115dbl sound pressure level (SPL) @ 1mW, impedance = 15ohm). Current = voltage/impedance = .34V/15ohm = .023amp. Power = current*voltage = .023amp*.34V = 7.82mW. You're ready to deliver nuclear winter to your cochlea...leave no hair standing.

With circumaural headphones you might have high impedance (300ohm-600ohm) and low efficiency 100dbl @ 1W. For such headphones you would need high an external amplifier. Still most large headphones can be adequately driven by a mobile device. For instance: Sennheiser HD700 large open back circumaural (105dbl SPL @ 1mW, impedance = 150ohm). Current = voltage/impedance = .34V/150ohm = .0023amp. Power = current*voltage = .0023amp*.34V = .782mW. If you like your music loud your SPL might be around 100dbl or more so a .34V source isn't going to cut it. An HTC One M9 or iPhone will have no problem though.

Thus, unless you want to use low efficiency headphones like the Sennheiser HD800 or Beyerdynamic DT990 a well designed mobile device can deliver plenty of power without a change in the form factor. That was all I was trying to say: high efficiency headphones should be able to be adequately driven from a mobile device with no external amplification. If that is not the case then I think the device design was inadequately considered even though it does not affect my applications. The statements from mosincredible are quite accurate and if you care about audio quality and spending your money wisely I strongly recommend you put in the effort to understand why he made the assertions that he did.

I recognize the simplifications I have done above but in trying to keep this under book length I believe it is more than adequate to convey the message. If you don’t let us know your thoughts albeit please make sure your argument contains a clear quantifiable (objective) basis.

---------- Post added at 04:50 PM ---------- Previous post was at 04:25 PM ----------

The Shure SE846 are very efficient headphones (114dbl @ 1mW and the lowest impedance at 8ohms that I know of). The 6P should drive them well. We will see when the gsmarena tests are published but the 6P could be among the best mobile devices for use with those headphones. The gsmarena tests linked earlier in the thread by mosincredible (relinked: http://www.gsmarena.com/huawei_p8-review-1263p7.php) show that the Huawei P8 has better audio quality than the LG G4 and Sony Z3 but trails the HTC One M9<iPhone 6S<Samsung S6 Edge+<Samsung S6. As such if Huawei managed to maintain or improve the audio system in the 6P it will have at least middle of the flagship pack audio system quality.

For high efficiency headphones like the SE846 I would not consider buying any DAC/amp that does not clearly list and show an improvement in the stereo crosstalk, distortion, noise, etc parameters shown in the gsmarena reviews. It is entirely possible that you will buy and use an inferior audio system and think it sounds better because of various manner of cognitive bias. This is very real and if the results from objective testing were the dominant concern in audiophile spending the market would look very different.