I did not play with settings and versions for a while but to enjoy the music played via picoplayer. I would like to share my latest setup and experience with you.
1. I am using "willem1" to play my majority 16/44.1 music, it causes the least problem and sounds best amongst all versions.
2. Use a notebook instead of a desktop PC as the Logitech Media Server sounds best so far. I am considering to get another Pi as the server to see if there will be another improvement
3. Direct connect my Pi with my notebook is better than via a router. For instruction, please visit here: (http://forums.slimdevices.com/showthread.php?99409-Picoplayer-without-DHCP-settings-and-USB-DAC-compatibility-reports)
4. Different power supply, Micro USB cable and LAN cable DO sounds quite differently in terms of quality. As most of us should have more than ONE in our home, please try different combinations to achieve the best sound.
5. Although the Pi should not need much power, however, my 5V 2.5A power supply with a labelled 2.1A capable Micro USB cable delivers a better punch and dynamics.