Thank you for the feedback.
- The speaker volume does not change when I connect headphones. This is odd, as I would expect the speakers are turned off when headphones are connected - as it happens in most other players
This is because there is used resistor voltage divider to attenuate the speaker signal for the headphone output. So a simple switch-over is not possible in the headphone socket.
- When pushing the volume up or down buttons, a klicking / scratching sound is hearable. It's not a big deal, but it is a bit annoying.
Indeed, there is this minor click sound. I'm sorry, this seems to be a feature of the audio codec and can't be avoided.
- As I'd like to connect another display: What kind of cable is necessary for the on-board display connector?
Here are some examples of such cable: http://www.molex.com/molex/products/listview.jsp?query=&offset=40&npp=20&sType=a&fs=&channel=products&autoNav=&path=+inmeta%3Acategory%3DCable+inmeta%3Apitchterminationinterface%3D1%25252E00mm&Itemlist=