Unfortunately, it is very hard to balance the function and the sound quality. sometimes we have to pay for the sound quality.
In fact, there are a hifi smartphone just released in China, called BBK X1 which with build in CS4398, a very good DAC chip, but the battery and the amp section limited the sound quality, so the sound quality is not as good as expected.
Anyway, E12 is a monster amp with plenty of power output, so it is not suitable for so many people because few people will use big cans on the go. but it do provide a possibility to people who want to do that , or make it more convenience at home because it
is easy to moved around.
Anyway, it is not the issues about FiiO because we have many options to our customer, from very tiny one (E6 ) to bigger one like E12, or even a amp which you can use to control the song on the amp ( E02i),