Double Bypass buffers
For user who like the sound of AD8656 and Bypass buffers you should try this
Double Bypass buffers.
It sound warmer and there are less sibilance and bass is tighter as well, compared to the bypass buffers that comes with the amplifier.
This one is really easy to make as well just solder a small wire joining pin 2 and 3, and another joining pin 5 and 6 on an empty socket.
Using the single buffers supplied by the factory The output resistance between the L/R amp and the headphone is about 6 ohm. Using the double buffers it is reduce by half or about 3 ohm. Allowing the L/R amp better control of the phone.
This combination sound really good. It is very good for battery life as well.
But is only suitable if you have an easy to drive IEM or headphone.