M-83
1000+ Head-Fier
In fact there are THREE version of AK100, namely AK100, AK100mk2, and AK100II. Among the three, AK100 and AK100mk2 were very similar and the most noticeable different is the output impedance dropped from 22ohm to 3ohm.
If you are referring to the original 22 ohm AK100, I'll suggest you to look otherwise, the 22ohm output impedance had been an issue as technically the output impedance of the your player should be lower then the rated impedance of your headphone. Industrial expert even stated that your headphone will perform best when the output impedance of your DAP is at least 1/8 that of your headphone impedance. So for instance if your IEMs are 16 ohms, the output impedance of your DAP should be 2 ohm or less. When AK100 was rated at 22ohm, you can expect the low impedance multi-BA IEMs are not pairing well.
AK100 is also not the best choice if you intend to hook up with a portable amplifier. The main problem is AK100 lack a dedicated line out connection. To connect with a portable amp., you are actually connected to the headphone output of AK100 and used that as a very low impedance "line out" when the volume is set to max. In my opinion, this is not as clean as a dedicated line out (that you can find in N6), in fact a lot of AK100 users finally resort to mod the player because of the 22ohm and line out issue, and that's where the famous RWAK100 came from:
http://redwineaudio.com/mods/rwak100
The AK100mk2 has rectified the output impedance problem but the line one problem remain untouched.
Thanks for the info Andy. Think I'm heading towards an N6, but want to avoid the early model serial nos that have had issues. Plus if I order from Shenzhen Audio in China, which courier do you think is most reliable?