@JamesFiiO , Hi!
Not so long ago, looking for new ways of sound transport/source, I wished Fiio had the features suited for my needs. At the end I decided to wait and use what I have in hands Ipod Nano+LOD cable+Fiio E12. Hope I made a right decision choosing “to wait” )
Below are my thought on the matter.
Target group. IMHO future sound transport has to satisfy these three groups:
a. Beginners thinking about future upgrade of headphones, AMP, AMP/DAC etc. So a device should have good DAC and amplifier powerful enough for 32Ohm IEM
b. Guys looking for upgrade for more/best amplification. So highly wanted are decent DAC and physically separate (sic) Line Out from Phone Out, so to completely remove all influence of embedded amplifier on a tract. An upgrade alternative to Fiio E12 like mine or E12A. I even agree on proprietary socket and chargers for $39.99 ))) but pls don’t combine Line Out with Phone Out tract of an amplifier.
c. Guys looking to use a transport together with AMP/DAC. Here the multitude of commutation options is most important. Nice example is using it with Fiio Q5.
About the design. Sorry but that what you show in first post doesn’t look good. The transport should be slim (10-12mm I think). It shouldn’t be think because we assume it is going to be used with external AMP or AMP/DAC. Even if the slickness will affect it autonomy. An example of ideal visual slickness and dimensions: AK Jr + E12A. All your products must be looking like big Hi-Fi components in one internal and external design.
OS. I think the best firmware would be your custom OS based on Linux.
Interface. Unless it’s odd job Android, ideal would be swipe oriented controls. Something based on gestures, like N9, Sailfish, or Ubuntu Touch.
Second SD card slot is excessive in my opinion. The price of space in a player and price of implementing it a lot more than a price for second, third or 10th card in your pocket.
Price. Be it $200-300 that would be ideal.
Your loyal customer