Developing a portable listening system that has the ability to provide balanced and single ended audio to headphones.  The purpose for this setup is to have a system that "approaches" desktop performance and provides a learning playground.   Using a portable DAC that has balanced output to a portable amplifier that has both balanced and singled ended inputs and outputs.  I am starting out with the iBasso system and will expand this as new equipment is purchased.  The first iteration with be with the stock PB2 and DB1 using iBasso cable between the units.  Sources will be MacBook Pro , EEE 1000HE, iPad and various DAPs.  Music is all ALAC and FLAC with some encoded at 24/96 from HDTracks. 
The iBasso PB2 has the ability to roll OP-Amps and Buffers.
Rear view of the DB1
The system is under construction.  I am balancing my DD770/80 headphones with Moon Audio Blue Dragon V3 cable.  Building adaptors to use both the Hirose and the plug for the RSA balanced Amps.  The iBasso hardware is on the way!  It looks like a SPDT switch will need to be added to the PB2 in order to have external access to the level setting for switching headphones.